diff --git a/src/core/server/index.ts b/src/core/server/index.ts
index e3df86ae78c4..670f58bfc1b7 100644
--- a/src/core/server/index.ts
+++ b/src/core/server/index.ts
@@ -307,8 +307,6 @@ export {
   SavedObjectsRepository,
   SavedObjectsDeleteByNamespaceOptions,
   SavedObjectsIncrementCounterOptions,
-  SavedObjectsComplexFieldMapping,
-  SavedObjectsCoreFieldMapping,
   SavedObjectsFieldMapping,
   SavedObjectsTypeMappingDefinition,
   SavedObjectsMappingProperties,
diff --git a/src/core/server/saved_objects/index.ts b/src/core/server/saved_objects/index.ts
index 6a8ab84e86f6..2ccee2333e99 100644
--- a/src/core/server/saved_objects/index.ts
+++ b/src/core/server/saved_objects/index.ts
@@ -65,8 +65,6 @@ export {
 } from './service/lib/repository';
 
 export {
-  SavedObjectsCoreFieldMapping,
-  SavedObjectsComplexFieldMapping,
   SavedObjectsFieldMapping,
   SavedObjectsMappingProperties,
   SavedObjectsTypeMappingDefinition,
diff --git a/src/core/server/saved_objects/mappings/index.ts b/src/core/server/saved_objects/mappings/index.ts
index fe6c38fda5ca..f5400384bbe3 100644
--- a/src/core/server/saved_objects/mappings/index.ts
+++ b/src/core/server/saved_objects/mappings/index.ts
@@ -31,8 +31,6 @@
  */
 export { getTypes, getProperty, getRootProperties, getRootPropertiesObjects } from './lib';
 export {
-  SavedObjectsComplexFieldMapping,
-  SavedObjectsCoreFieldMapping,
   SavedObjectsTypeMappingDefinition,
   SavedObjectsTypeMappingDefinitions,
   SavedObjectsMappingProperties,
diff --git a/src/core/server/saved_objects/mappings/lib/get_property.test.ts b/src/core/server/saved_objects/mappings/lib/get_property.test.ts
index a05d671f1a9e..d23d64648b20 100644
--- a/src/core/server/saved_objects/mappings/lib/get_property.test.ts
+++ b/src/core/server/saved_objects/mappings/lib/get_property.test.ts
@@ -53,7 +53,7 @@ const MAPPINGS = {
       },
     },
   },
-};
+} as const;
 
 function runTest(key: string | string[], mapping: IndexMapping | SavedObjectsFieldMapping) {
   expect(typeof key === 'string' || Array.isArray(key)).toBeTruthy();
diff --git a/src/core/server/saved_objects/mappings/lib/get_property.ts b/src/core/server/saved_objects/mappings/lib/get_property.ts
index 012907dd4d81..03a9ef1a02a5 100644
--- a/src/core/server/saved_objects/mappings/lib/get_property.ts
+++ b/src/core/server/saved_objects/mappings/lib/get_property.ts
@@ -26,7 +26,7 @@
  */
 
 import { toPath } from 'lodash';
-import { SavedObjectsCoreFieldMapping, SavedObjectsFieldMapping, IndexMapping } from '../types';
+import { SavedObjectsFieldMapping, IndexMapping } from '../types';
 
 function getPropertyMappingFromObjectMapping(
   mapping: IndexMapping | SavedObjectsFieldMapping,
@@ -34,7 +34,7 @@ function getPropertyMappingFromObjectMapping(
 ): SavedObjectsFieldMapping | undefined {
   const props =
     (mapping && (mapping as IndexMapping).properties) ||
-    (mapping && (mapping as SavedObjectsCoreFieldMapping).fields);
+    (mapping && (mapping as SavedObjectsFieldMapping).fields);
 
   if (!props) {
     return undefined;
diff --git a/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.test.ts b/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.test.ts
index fc4a76164778..00ca1110df2a 100644
--- a/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.test.ts
+++ b/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.test.ts
@@ -34,7 +34,7 @@ test(`returns single object with properties`, () => {
         properties: {},
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -51,7 +51,7 @@ test(`returns single object with type === 'object'`, () => {
         type: 'object',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -71,7 +71,7 @@ test(`returns two objects with properties`, () => {
         properties: {},
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -94,7 +94,7 @@ test(`returns two objects with type === 'object'`, () => {
         type: 'object',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -114,7 +114,7 @@ test(`excludes objects without properties and type of keyword`, () => {
         type: 'keyword',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({});
@@ -130,7 +130,7 @@ test(`excludes two objects without properties and type of keyword`, () => {
         type: 'keyword',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({});
@@ -146,7 +146,7 @@ test(`includes one object with properties and excludes one object without proper
         type: 'keyword',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -166,7 +166,7 @@ test(`includes one object with type === 'object' and excludes one object without
         type: 'keyword',
       },
     },
-  };
+  } as const;
 
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
@@ -189,7 +189,7 @@ test('excludes references and migrationVersion which are part of the blacklist',
         type: 'object',
       },
     },
-  };
+  } as const;
   const result = getRootPropertiesObjects(mappings);
   expect(result).toEqual({
     foo: {
diff --git a/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.ts b/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.ts
index 30e82c80e92d..c0b8adc5a5ae 100644
--- a/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.ts
+++ b/src/core/server/saved_objects/mappings/lib/get_root_properties_objects.ts
@@ -25,11 +25,7 @@
  * under the License.
  */
 
-import {
-  SavedObjectsComplexFieldMapping,
-  IndexMapping,
-  SavedObjectsMappingProperties,
-} from '../types';
+import { SavedObjectsFieldMapping, IndexMapping, SavedObjectsMappingProperties } from '../types';
 import { getRootProperties } from './get_root_properties';
 
 /**
@@ -55,7 +51,7 @@ export function getRootPropertiesObjects(mappings: IndexMapping) {
     // we consider the existence of the properties or type of object to designate that this is an object datatype
     if (
       !omittedRootProps.includes(key) &&
-      ((value as SavedObjectsComplexFieldMapping).properties || value.type === 'object')
+      ((value as SavedObjectsFieldMapping).properties || value.type === 'object')
     ) {
       acc[key] = value;
     }
diff --git a/src/core/server/saved_objects/mappings/types.ts b/src/core/server/saved_objects/mappings/types.ts
index b5fbac25c470..e14b3febb709 100644
--- a/src/core/server/saved_objects/mappings/types.ts
+++ b/src/core/server/saved_objects/mappings/types.ts
@@ -30,6 +30,8 @@
  * GitHub history for details.
  */
 
+import type { opensearchtypes } from '@opensearch-project/opensearch';
+
 /**
  * Describe a saved object type mapping.
  *
@@ -117,13 +119,21 @@ export interface SavedObjectsMappingProperties {
  *
  * @public
  */
-export type SavedObjectsFieldMapping =
-  | SavedObjectsCoreFieldMapping
-  | SavedObjectsComplexFieldMapping;
+export type SavedObjectsFieldMapping = opensearchtypes.MappingProperty & {
+  /**
+   * The dynamic property of the mapping, either `false` or `'strict'`. If
+   * unspecified `dynamic: 'strict'` will be inherited from the top-level
+   * index mappings.
+   *
+   * Note: To limit the number of mapping fields Saved Object types should
+   * *never* use `dynamic: true`.
+   */
+  dynamic?: false | 'strict';
+};
 
 /** @internal */
 export interface IndexMapping {
-  dynamic?: string;
+  dynamic?: boolean | 'strict';
   properties: SavedObjectsMappingProperties;
   _meta?: IndexMappingMeta;
 }
@@ -135,42 +145,3 @@ export interface IndexMappingMeta {
   // the md5 hash of that mapping's value when the index was created.
   migrationMappingPropertyHashes?: { [k: string]: string };
 }
-
-/**
- * See {@link SavedObjectsFieldMapping} for documentation.
- *
- * @public
- */
-export interface SavedObjectsCoreFieldMapping {
-  type: string;
-  null_value?: number | boolean | string;
-  index?: boolean;
-  doc_values?: boolean;
-  fields?: {
-    [subfield: string]: {
-      type: string;
-      ignore_above?: number;
-    };
-  };
-}
-
-/**
- * See {@link SavedObjectsFieldMapping} for documentation.
- *
- * @public
- */
-export interface SavedObjectsComplexFieldMapping {
-  /**
-   * The dynamic property of the mapping, either `false` or `'strict'`. If
-   * unspecified `dynamic: 'strict'` will be inherited from the top-level
-   * index mappings.
-   *
-   * Note: To limit the number of mapping fields Saved Object types should
-   * *never* use `dynamic: true`.
-   */
-  dynamic?: false | 'strict';
-  enabled?: boolean;
-  doc_values?: boolean;
-  type?: string;
-  properties: SavedObjectsMappingProperties;
-}
diff --git a/src/core/server/saved_objects/migrations/core/__snapshots__/opensearch_index.test.ts.snap b/src/core/server/saved_objects/migrations/core/__snapshots__/opensearch_index.test.ts.snap
index 6bd567be204d..a9fa5ed34ed5 100644
--- a/src/core/server/saved_objects/migrations/core/__snapshots__/opensearch_index.test.ts.snap
+++ b/src/core/server/saved_objects/migrations/core/__snapshots__/opensearch_index.test.ts.snap
@@ -1,6 +1,6 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`ElasticIndex write writes documents in bulk to the index 1`] = `
+exports[`OpenSearchIndex write writes documents in bulk to the index 1`] = `
 Array [
   Object {
     "body": Array [
diff --git a/src/core/server/saved_objects/migrations/core/build_active_mappings.test.ts b/src/core/server/saved_objects/migrations/core/build_active_mappings.test.ts
index 81aa395bd702..17f64b3e488e 100644
--- a/src/core/server/saved_objects/migrations/core/build_active_mappings.test.ts
+++ b/src/core/server/saved_objects/migrations/core/build_active_mappings.test.ts
@@ -38,19 +38,19 @@ describe('buildActiveMappings', () => {
     const properties = {
       aaa: { type: 'text' },
       bbb: { type: 'long' },
-    };
+    } as const;
 
     expect(buildActiveMappings(properties)).toMatchSnapshot();
   });
 
   test('disallows duplicate mappings', () => {
-    const properties = { type: { type: 'long' } };
+    const properties = { type: { type: 'long' } } as const;
 
     expect(() => buildActiveMappings(properties)).toThrow(/Cannot redefine core mapping \"type\"/);
   });
 
   test('disallows mappings with leading underscore', () => {
-    const properties = { _hm: { type: 'keyword' } };
+    const properties = { _hm: { type: 'keyword' } } as const;
 
     expect(() => buildActiveMappings(properties)).toThrow(
       /Invalid mapping \"_hm\"\. Mappings cannot start with _/
@@ -79,7 +79,7 @@ describe('buildActiveMappings', () => {
       aaa: { type: 'keyword', fields: { a: { type: 'keyword' }, b: { type: 'text' } } },
       bbb: { fields: { b: { type: 'text' }, a: { type: 'keyword' } }, type: 'keyword' },
       ccc: { fields: { b: { type: 'text' }, a: { type: 'text' } }, type: 'keyword' },
-    };
+    } as const;
 
     const mappings = buildActiveMappings(properties);
     const hashes = mappings._meta!.migrationMappingPropertyHashes!;
@@ -183,6 +183,7 @@ describe('diffMappings', () => {
       _meta: {
         migrationMappingPropertyHashes: { foo: 'bar' },
       },
+      // @ts-expect-error
       dynamic: 'abcde',
       properties: {},
     };
diff --git a/src/core/server/saved_objects/migrations/core/build_index_map.test.ts b/src/core/server/saved_objects/migrations/core/build_index_map.test.ts
index 64fc54d3640e..eb46066f1864 100644
--- a/src/core/server/saved_objects/migrations/core/build_index_map.test.ts
+++ b/src/core/server/saved_objects/migrations/core/build_index_map.test.ts
@@ -55,7 +55,7 @@ test('mappings without index pattern goes to default index', () => {
       type1: {
         properties: {
           field1: {
-            type: 'string',
+            type: 'text',
           },
         },
       },
@@ -67,7 +67,7 @@ test('mappings without index pattern goes to default index', () => {
         type1: {
           properties: {
             field1: {
-              type: 'string',
+              type: 'text',
             },
           },
         },
@@ -88,7 +88,7 @@ test(`mappings with custom index pattern doesn't go to default index`, () => {
       type1: {
         properties: {
           field1: {
-            type: 'string',
+            type: 'text',
           },
         },
       },
@@ -100,7 +100,7 @@ test(`mappings with custom index pattern doesn't go to default index`, () => {
         type1: {
           properties: {
             field1: {
-              type: 'string',
+              type: 'text',
             },
           },
         },
@@ -122,7 +122,7 @@ test('creating a script gets added to the index pattern', () => {
       type1: {
         properties: {
           field1: {
-            type: 'string',
+            type: 'text',
           },
         },
       },
@@ -135,7 +135,7 @@ test('creating a script gets added to the index pattern', () => {
         type1: {
           properties: {
             field1: {
-              type: 'string',
+              type: 'text',
             },
           },
         },
@@ -163,18 +163,18 @@ test('throws when two scripts are defined for an index pattern', () => {
     type1: {
       properties: {
         field1: {
-          type: 'string',
+          type: 'text',
         },
       },
     },
     type2: {
       properties: {
         field1: {
-          type: 'string',
+          type: 'text',
         },
       },
     },
-  };
+  } as const;
   expect(() =>
     createIndexMap({
       opensearchDashboardsIndexName: defaultIndex,
diff --git a/src/core/server/saved_objects/migrations/core/call_cluster.ts b/src/core/server/saved_objects/migrations/core/call_cluster.ts
index f896da60c005..c3e6a72f937a 100644
--- a/src/core/server/saved_objects/migrations/core/call_cluster.ts
+++ b/src/core/server/saved_objects/migrations/core/call_cluster.ts
@@ -31,11 +31,15 @@
  * funcationality contained here.
  */
 
+import { opensearchtypes } from '@opensearch-project/opensearch';
 import { IndexMapping } from '../../mappings';
 
 export interface CallCluster {
   (path: 'bulk', opts: { body: object[] }): Promise<BulkResult>;
-  (path: 'count', opts: CountOpts): Promise<{ count: number; _shards: ShardsInfo }>;
+  (path: 'count', opts: CountOpts): Promise<{
+    count: number;
+    _shards: opensearchtypes.ShardStatistics;
+  }>;
   (path: 'clearScroll', opts: { scrollId: string }): Promise<any>;
   (path: 'indices.create' | 'indices.delete', opts: IndexCreationOpts): Promise<any>;
   (path: 'indices.exists', opts: IndexOpts): Promise<boolean>;
@@ -172,14 +176,7 @@ export interface SearchResults {
     hits: RawDoc[];
   };
   _scroll_id?: string;
-  _shards: ShardsInfo;
-}
-
-export interface ShardsInfo {
-  total: number;
-  successful: number;
-  skipped: number;
-  failed: number;
+  _shards: opensearchtypes.ShardStatistics;
 }
 
 export interface ErrorResponse {
diff --git a/src/core/server/saved_objects/migrations/core/index_migrator.test.ts b/src/core/server/saved_objects/migrations/core/index_migrator.test.ts
index 8058f20ce3d2..2fefbe04133e 100644
--- a/src/core/server/saved_objects/migrations/core/index_migrator.test.ts
+++ b/src/core/server/saved_objects/migrations/core/index_migrator.test.ts
@@ -26,6 +26,7 @@
  */
 
 import _ from 'lodash';
+import type { opensearchtypes } from '@opensearch-project/opensearch';
 import { opensearchClientMock } from '../../../opensearch/client/mocks';
 import { SavedObjectUnsanitizedDoc, SavedObjectsSerializer } from '../../serialization';
 import { SavedObjectTypeRegistry } from '../../saved_objects_type_registry';
@@ -454,23 +455,28 @@ function withIndex(
     opensearchClientMock.createSuccessTransportRequestPromise({
       task: 'zeid',
       _shards: { successful: 1, total: 1 },
-    })
+    } as opensearchtypes.ReindexResponse)
   );
   client.tasks.get.mockReturnValue(
-    opensearchClientMock.createSuccessTransportRequestPromise({ completed: true })
+    opensearchClientMock.createSuccessTransportRequestPromise({
+      completed: true,
+    } as opensearchtypes.TaskGetResponse)
   );
   client.search.mockReturnValue(
-    opensearchClientMock.createSuccessTransportRequestPromise(searchResult(0))
+    opensearchClientMock.createSuccessTransportRequestPromise(searchResult(0) as any)
   );
   client.bulk.mockReturnValue(
-    opensearchClientMock.createSuccessTransportRequestPromise({ items: [] })
+    opensearchClientMock.createSuccessTransportRequestPromise({
+      items: [] as any[],
+    } as opensearchtypes.BulkResponse)
   );
   client.count.mockReturnValue(
     opensearchClientMock.createSuccessTransportRequestPromise({
       count: numOutOfDate,
       _shards: { successful: 1, total: 1 },
-    })
+    } as opensearchtypes.CountResponse)
   );
+  // @ts-expect-error
   client.scroll.mockImplementation(() => {
     if (scrollCallCounter <= docs.length) {
       const result = searchResult(scrollCallCounter);
diff --git a/src/core/server/saved_objects/migrations/core/index_migrator.ts b/src/core/server/saved_objects/migrations/core/index_migrator.ts
index 5c6a01246991..17ac3f752917 100644
--- a/src/core/server/saved_objects/migrations/core/index_migrator.ts
+++ b/src/core/server/saved_objects/migrations/core/index_migrator.ts
@@ -169,7 +169,7 @@ async function deleteIndexTemplates({ client, log, obsoleteIndexTemplatePattern
 
   log.info(`Removing index templates: ${templateNames}`);
 
-  return Promise.all(templateNames.map((name) => client.indices.deleteTemplate({ name })));
+  return Promise.all(templateNames.map((name) => client.indices.deleteTemplate({ name: name! })));
 }
 
 /**
@@ -207,6 +207,7 @@ async function migrateSourceToDest(context: Context) {
     await Index.write(
       client,
       dest.indexName,
+      // @ts-expect-error @opensearch-project/opensearch _source is optional
       await migrateRawDocs(serializer, documentMigrator.migrate, docs, log)
     );
   }
diff --git a/src/core/server/saved_objects/migrations/core/migration_context.test.ts b/src/core/server/saved_objects/migrations/core/migration_context.test.ts
index 43a8ec983533..ce1324183cbe 100644
--- a/src/core/server/saved_objects/migrations/core/migration_context.test.ts
+++ b/src/core/server/saved_objects/migrations/core/migration_context.test.ts
@@ -50,7 +50,7 @@ describe('disableUnknownTypeMappingFields', () => {
         },
       },
     },
-  };
+  } as const;
   const activeMappings = {
     _meta: {
       migrationMappingPropertyHashes: {
@@ -65,7 +65,7 @@ describe('disableUnknownTypeMappingFields', () => {
         },
       },
     },
-  };
+  } as const;
   const targetMappings = disableUnknownTypeMappingFields(activeMappings, sourceMappings);
 
   it('disables complex field mappings from unknown types in the source mappings', () => {
diff --git a/src/core/server/saved_objects/migrations/core/opensearch_index.test.ts b/src/core/server/saved_objects/migrations/core/opensearch_index.test.ts
index c5c0473fe6b5..4edbbfd9b1f9 100644
--- a/src/core/server/saved_objects/migrations/core/opensearch_index.test.ts
+++ b/src/core/server/saved_objects/migrations/core/opensearch_index.test.ts
@@ -25,11 +25,12 @@
  * under the License.
  */
 
+import type { opensearchtypes } from '@opensearch-project/opensearch';
 import _ from 'lodash';
 import { opensearchClientMock } from '../../../opensearch/client/mocks';
 import * as Index from './opensearch_index';
 
-describe('ElasticIndex', () => {
+describe('OpenSearchIndex', () => {
   let client: ReturnType<typeof opensearchClientMock.createOpenSearchClient>;
 
   beforeEach(() => {
@@ -61,9 +62,11 @@ describe('ElasticIndex', () => {
         return opensearchClientMock.createSuccessTransportRequestPromise({
           [index]: {
             aliases: { foo: index },
-            mappings: { spock: { dynamic: 'strict', properties: { a: 'b' } } },
+            // @ts-expect-error
+            mappings: { spock: { dynamic: 'strict', properties: { a: 'b' } as any } },
+            settings: {},
           },
-        });
+        } as opensearchtypes.IndicesGetResponse);
       });
 
       await expect(Index.fetchInfo(client, '.baz')).rejects.toThrow(
@@ -78,11 +81,13 @@ describe('ElasticIndex', () => {
           [index]: {
             aliases: { foo: index },
             mappings: {
-              doc: { dynamic: 'strict', properties: { a: 'b' } },
-              doctor: { dynamic: 'strict', properties: { a: 'b' } },
+              // @ts-expect-error
+              doc: { dynamic: 'strict', properties: { a: 'b' } as any },
+              doctor: { dynamic: 'strict', properties: { a: 'b' } as any },
             },
+            settings: {},
           },
-        });
+        } as opensearchtypes.IndicesGetResponse);
       });
 
       await expect(Index.fetchInfo(client, '.baz')).rejects.toThrow(
@@ -96,9 +101,10 @@ describe('ElasticIndex', () => {
         return opensearchClientMock.createSuccessTransportRequestPromise({
           [index]: {
             aliases: { foo: index },
-            mappings: { dynamic: 'strict', properties: { a: 'b' } },
+            mappings: { dynamic: 'strict', properties: { a: 'b' } as any },
+            settings: {},
           },
-        });
+        } as opensearchtypes.IndicesGetResponse);
       });
 
       const info = await Index.fetchInfo(client, '.baz');
@@ -107,6 +113,7 @@ describe('ElasticIndex', () => {
         mappings: { dynamic: 'strict', properties: { a: 'b' } },
         exists: true,
         indexName: '.baz',
+        settings: {},
       });
     });
   });
@@ -167,7 +174,7 @@ describe('ElasticIndex', () => {
     test('removes existing alias', async () => {
       client.indices.getAlias.mockResolvedValue(
         opensearchClientMock.createSuccessTransportRequestPromise({
-          '.my-fanci-index': '.muchacha',
+          '.my-fanci-index': { aliases: { '.muchacha': {} } },
         })
       );
 
@@ -190,7 +197,7 @@ describe('ElasticIndex', () => {
     test('allows custom alias actions', async () => {
       client.indices.getAlias.mockResolvedValue(
         opensearchClientMock.createSuccessTransportRequestPromise({
-          '.my-fanci-index': '.muchacha',
+          '.my-fanci-index': { aliases: { '.muchacha': {} } },
         })
       );
 
@@ -218,14 +225,18 @@ describe('ElasticIndex', () => {
     test('it creates the destination index, then reindexes to it', async () => {
       client.indices.getAlias.mockResolvedValue(
         opensearchClientMock.createSuccessTransportRequestPromise({
-          '.my-fanci-index': '.muchacha',
+          '.my-fanci-index': { aliases: { '.muchacha': {} } },
         })
       );
       client.reindex.mockResolvedValue(
-        opensearchClientMock.createSuccessTransportRequestPromise({ task: 'abc' })
+        opensearchClientMock.createSuccessTransportRequestPromise({
+          task: 'abc',
+        } as opensearchtypes.ReindexResponse)
       );
       client.tasks.get.mockResolvedValue(
-        opensearchClientMock.createSuccessTransportRequestPromise({ completed: true })
+        opensearchClientMock.createSuccessTransportRequestPromise({
+          completed: true,
+        } as opensearchtypes.TaskGetResponse)
       );
 
       const info = {
@@ -233,10 +244,10 @@ describe('ElasticIndex', () => {
         exists: true,
         indexName: '.ze-index',
         mappings: {
-          dynamic: 'strict',
+          dynamic: 'strict' as const,
           properties: { foo: { type: 'keyword' } },
         },
-      };
+      } as const;
 
       await Index.convertToAlias(
         client,
@@ -292,13 +303,16 @@ describe('ElasticIndex', () => {
     test('throws error if re-index task fails', async () => {
       client.indices.getAlias.mockResolvedValue(
         opensearchClientMock.createSuccessTransportRequestPromise({
-          '.my-fanci-index': '.muchacha',
+          '.my-fanci-index': { aliases: { '.muchacha': {} } },
         })
       );
       client.reindex.mockResolvedValue(
-        opensearchClientMock.createSuccessTransportRequestPromise({ task: 'abc' })
+        opensearchClientMock.createSuccessTransportRequestPromise({
+          task: 'abc',
+        } as opensearchtypes.ReindexResponse)
       );
       client.tasks.get.mockResolvedValue(
+        // @ts-expect-error @opensearch-project/opensearch GetTaskResponse requires a `task` property even on errors
         opensearchClientMock.createSuccessTransportRequestPromise({
           completed: true,
           error: {
@@ -306,7 +320,7 @@ describe('ElasticIndex', () => {
             reason: 'all shards failed',
             failed_shards: [],
           },
-        })
+        } as opensearchtypes.TaskGetResponse)
       );
 
       const info = {
@@ -319,6 +333,7 @@ describe('ElasticIndex', () => {
         },
       };
 
+      // @ts-expect-error
       await expect(Index.convertToAlias(client, info, '.muchacha', 10)).rejects.toThrow(
         /Re-index failed \[search_phase_execution_exception\] all shards failed/
       );
@@ -352,7 +367,9 @@ describe('ElasticIndex', () => {
   describe('write', () => {
     test('writes documents in bulk to the index', async () => {
       client.bulk.mockResolvedValue(
-        opensearchClientMock.createSuccessTransportRequestPromise({ items: [] })
+        opensearchClientMock.createSuccessTransportRequestPromise({
+          items: [] as any[],
+        } as opensearchtypes.BulkResponse)
       );
 
       const index = '.myalias';
@@ -389,7 +406,7 @@ describe('ElasticIndex', () => {
       client.bulk.mockResolvedValue(
         opensearchClientMock.createSuccessTransportRequestPromise({
           items: [{ index: { error: { type: 'shazm', reason: 'dern' } } }],
-        })
+        } as opensearchtypes.BulkResponse)
       );
 
       const index = '.myalias';
diff --git a/src/core/server/saved_objects/migrations/core/opensearch_index.ts b/src/core/server/saved_objects/migrations/core/opensearch_index.ts
index aca47217d68d..dc5d8b507c5b 100644
--- a/src/core/server/saved_objects/migrations/core/opensearch_index.ts
+++ b/src/core/server/saved_objects/migrations/core/opensearch_index.ts
@@ -31,11 +31,12 @@
  */
 
 import _ from 'lodash';
+import { opensearchtypes } from '@opensearch-project/opensearch';
 import { MigrationOpenSearchClient } from './migration_opensearch_client';
-import { CountResponse, SearchResponse } from '../../../opensearch';
+import { CountResponse } from '../../../opensearch';
 import { IndexMapping } from '../../mappings';
 import { SavedObjectsMigrationVersion } from '../../types';
-import { AliasAction, RawDoc, ShardsInfo } from './call_cluster';
+import { AliasAction, RawDoc } from './call_cluster';
 import { SavedObjectsRawDocSource } from '../../serialization';
 
 const settings = { number_of_shards: 1, auto_expand_replicas: '0-1' };
@@ -68,6 +69,7 @@ export async function fetchInfo(
 
   const [indexName, indexInfo] = Object.entries(body)[0];
 
+  // @ts-expect-error @opensearch-project/opensearch IndexState.alias and IndexState.mappings should be required
   return assertIsSupportedIndex({ ...indexInfo, exists: true, indexName });
 }
 
@@ -91,11 +93,11 @@ export function reader(
 
   const nextBatch = () =>
     scrollId !== undefined
-      ? client.scroll<SearchResponse<SavedObjectsRawDocSource>>({
+      ? client.scroll<SavedObjectsRawDocSource>({
           scroll,
           scroll_id: scrollId,
         })
-      : client.search<SearchResponse<SavedObjectsRawDocSource>>({
+      : client.search<SavedObjectsRawDocSource>({
           body: { size: batchSize },
           index,
           scroll,
@@ -147,7 +149,7 @@ export async function write(client: MigrationOpenSearchClient, index: string, do
     return;
   }
 
-  const exception: any = new Error(err.index.error!.reason);
+  const exception: any = new Error(err.index!.error!.reason);
   exception.detail = err;
   throw exception;
 }
@@ -319,7 +321,7 @@ function assertIsSupportedIndex(indexInfo: FullIndexInfo) {
  * Object indices should only ever have a single shard. This is more to handle
  * instances where customers manually expand the shards of an index.
  */
-function assertResponseIncludeAllShards({ _shards }: { _shards: ShardsInfo }) {
+function assertResponseIncludeAllShards({ _shards }: { _shards: opensearchtypes.ShardStatistics }) {
   if (!_.has(_shards, 'total') || !_.has(_shards, 'successful')) {
     return;
   }
@@ -372,7 +374,7 @@ async function reindex(
     await new Promise((r) => setTimeout(r, pollInterval));
 
     const { body } = await client.tasks.get({
-      task_id: task,
+      task_id: String(task),
     });
 
     if (body.error) {
diff --git a/src/core/server/saved_objects/migrations/opensearch_dashboards/opensearch_dashboards_migrator.test.ts b/src/core/server/saved_objects/migrations/opensearch_dashboards/opensearch_dashboards_migrator.test.ts
index e3daad27d6fc..6dcf531880fc 100644
--- a/src/core/server/saved_objects/migrations/opensearch_dashboards/opensearch_dashboards_migrator.test.ts
+++ b/src/core/server/saved_objects/migrations/opensearch_dashboards/opensearch_dashboards_migrator.test.ts
@@ -81,7 +81,8 @@ describe('OpenSearchDashboardsMigrator', () => {
 
       options.client.cat.templates.mockReturnValue(
         opensearchClientMock.createSuccessTransportRequestPromise(
-          { templates: [] },
+          // @ts-expect-error
+          { templates: [] } as CatTemplatesResponse,
           { statusCode: 404 }
         )
       );
@@ -105,7 +106,8 @@ describe('OpenSearchDashboardsMigrator', () => {
 
       options.client.cat.templates.mockReturnValue(
         opensearchClientMock.createSuccessTransportRequestPromise(
-          { templates: [] },
+          // @ts-expect-error
+          { templates: [] } as CatTemplatesResponse,
           { statusCode: 404 }
         )
       );
diff --git a/src/core/server/saved_objects/saved_objects_type_registry.ts b/src/core/server/saved_objects/saved_objects_type_registry.ts
index 599f9eb0cfa6..57a3f9aedb3a 100644
--- a/src/core/server/saved_objects/saved_objects_type_registry.ts
+++ b/src/core/server/saved_objects/saved_objects_type_registry.ts
@@ -56,7 +56,7 @@ export class SavedObjectTypeRegistry {
     if (this.types.has(type.name)) {
       throw new Error(`Type '${type.name}' is already registered`);
     }
-    this.types.set(type.name, deepFreeze(type));
+    this.types.set(type.name, deepFreeze(type) as SavedObjectsType);
   }
 
   /**
diff --git a/src/core/server/saved_objects/service/lib/filter_utils.test.ts b/src/core/server/saved_objects/service/lib/filter_utils.test.ts
index 4e1245e37212..397bac7e37be 100644
--- a/src/core/server/saved_objects/service/lib/filter_utils.test.ts
+++ b/src/core/server/saved_objects/service/lib/filter_utils.test.ts
@@ -48,7 +48,7 @@ const mockMappings = {
           type: 'text',
         },
         bytes: {
-          type: 'number',
+          type: 'integer',
         },
       },
     },
@@ -92,7 +92,7 @@ const mockMappings = {
       },
     },
   },
-};
+} as const;
 
 describe('Filter Utils', () => {
   describe('#validateConvertFilterToKueryNode', () => {
diff --git a/src/core/server/saved_objects/service/lib/repository.test.js b/src/core/server/saved_objects/service/lib/repository.test.js
index b2ebc43db362..6c47a91e315e 100644
--- a/src/core/server/saved_objects/service/lib/repository.test.js
+++ b/src/core/server/saved_objects/service/lib/repository.test.js
@@ -3352,6 +3352,7 @@ describe('SavedObjectsRepository', () => {
           id: '6.0.0-alpha1',
           ...mockTimestampFields,
           version: mockVersion,
+          references: [],
           attributes: {
             buildNum: 8468,
             defaultIndex: 'logstash-*',
diff --git a/src/core/server/saved_objects/service/lib/repository.ts b/src/core/server/saved_objects/service/lib/repository.ts
index 01ef8fdb1fd5..123def8d3c31 100644
--- a/src/core/server/saved_objects/service/lib/repository.ts
+++ b/src/core/server/saved_objects/service/lib/repository.ts
@@ -31,13 +31,10 @@
  */
 
 import { omit } from 'lodash';
+import type { opensearchtypes } from '@opensearch-project/opensearch';
 import uuid from 'uuid';
-import {
-  OpenSearchClient,
-  DeleteDocumentResponse,
-  GetResponse,
-  SearchResponse,
-} from '../../../opensearch/';
+import type { ISavedObjectTypeRegistry } from '../../saved_objects_type_registry';
+import { OpenSearchClient, DeleteDocumentResponse } from '../../../opensearch/';
 import { getRootPropertiesObjects, IndexMapping } from '../../mappings';
 import {
   createRepositoryOpenSearchClient,
@@ -399,8 +396,8 @@ export class SavedObjectsRepository {
         return expectedBulkGetResult;
       }
 
-      let savedObjectNamespace;
-      let savedObjectNamespaces;
+      let savedObjectNamespace: string | undefined;
+      let savedObjectNamespaces: string[] | undefined;
       let versionProperties;
       const {
         opensearchRequestIndex,
@@ -412,8 +409,9 @@ export class SavedObjectsRepository {
         const actualResult = indexFound
           ? bulkGetResponse?.body.docs[opensearchRequestIndex]
           : undefined;
-        const docFound = indexFound && actualResult.found === true;
-        if (docFound && !this.rawDocExistsInNamespace(actualResult, namespace)) {
+        const docFound = indexFound && actualResult?.found === true;
+        // @ts-expect-error MultiGetHit._source is optional
+        if (docFound && !this.rawDocExistsInNamespace(actualResult!, namespace)) {
           const { id, type } = object;
           return {
             tag: 'Left' as 'Left',
@@ -428,11 +426,14 @@ export class SavedObjectsRepository {
           };
         }
         savedObjectNamespaces =
-          initialNamespaces || getSavedObjectNamespaces(namespace, docFound && actualResult);
+          initialNamespaces ||
+          // @ts-expect-error MultiGetHit._source is optional
+          getSavedObjectNamespaces(namespace, docFound ? actualResult : undefined);
+        // @ts-expect-error MultiGetHit._source is optional
         versionProperties = getExpectedVersionProperties(version, actualResult);
       } else {
         if (this._registry.isSingleNamespace(object.type)) {
-          savedObjectNamespace = namespace;
+          savedObjectNamespace = initialNamespaces ? initialNamespaces[0] : namespace;
         } else if (this._registry.isMultiNamespace(object.type)) {
           savedObjectNamespaces = initialNamespaces || getSavedObjectNamespaces(namespace);
         }
@@ -486,7 +487,7 @@ export class SavedObjectsRepository {
 
         const { requestedId, rawMigratedDoc, opensearchRequestIndex } = expectedResult.value;
         const { error, ...rawResponse } = Object.values(
-          bulkResponse?.body.items[opensearchRequestIndex]
+          bulkResponse?.body.items[opensearchRequestIndex] ?? {}
         )[0] as any;
 
         if (error) {
@@ -572,13 +573,14 @@ export class SavedObjectsRepository {
 
       const { type, id, opensearchRequestIndex } = expectedResult.value;
       const doc = bulkGetResponse?.body.docs[opensearchRequestIndex];
-      if (doc.found) {
+      if (doc?.found) {
         errors.push({
           id,
           type,
           error: {
             ...errorContent(SavedObjectsErrorHelpers.createConflictError(type, id)),
-            ...(!this.rawDocExistsInNamespace(doc, namespace) && {
+            // @ts-expect-error MultiGetHit._source is optional
+            ...(!this.rawDocExistsInNamespace(doc!, namespace) && {
               metadata: { isNotOverwritable: true },
             }),
           },
@@ -813,9 +815,12 @@ export class SavedObjectsRepository {
       },
     };
 
-    const { body, statusCode } = await this.client.search<SearchResponse<any>>(opensearchOptions, {
-      ignore: [404],
-    });
+    const { body, statusCode } = await this.client.search<SavedObjectsRawDocSource>(
+      opensearchOptions,
+      {
+        ignore: [404],
+      }
+    );
     if (statusCode === 404) {
       // 404 is only possible here if the index is missing, which
       // we don't want to leak, see "404s from missing index" above
@@ -832,9 +837,12 @@ export class SavedObjectsRepository {
       per_page: perPage,
       total: body.hits.total,
       saved_objects: body.hits.hits.map(
-        (hit: SavedObjectsRawDoc): SavedObjectsFindResult => ({
+        (hit: opensearchtypes.SearchHit<SavedObjectsRawDocSource>): SavedObjectsFindResult => ({
+          // @ts-expect-error @opensearch-project/opensearch _source is optional
           ...this._rawToSavedObject(hit),
-          score: (hit as any)._score,
+          score: hit._score!,
+          // @ts-expect-error @opensearch-project/opensearch _source is optional
+          sort: hit.sort,
         })
       ),
     } as SavedObjectsFindResponse<T>;
@@ -917,7 +925,8 @@ export class SavedObjectsRepository {
         const { type, id, opensearchRequestIndex } = expectedResult.value;
         const doc = bulkGetResponse?.body.docs[opensearchRequestIndex];
 
-        if (!doc.found || !this.rawDocExistsInNamespace(doc, namespace)) {
+        // @ts-expect-error MultiGetHit._source is optional
+        if (!doc?.found || !this.rawDocExistsInNamespace(doc, namespace)) {
           return ({
             id,
             type,
@@ -925,25 +934,8 @@ export class SavedObjectsRepository {
           } as any) as SavedObject<T>;
         }
 
-        const { originId, updated_at: updatedAt } = doc._source;
-        let namespaces = [];
-        if (!this._registry.isNamespaceAgnostic(type)) {
-          namespaces = doc._source.namespaces ?? [
-            SavedObjectsUtils.namespaceIdToString(doc._source.namespace),
-          ];
-        }
-
-        return {
-          id,
-          type,
-          namespaces,
-          ...(originId && { originId }),
-          ...(updatedAt && { updated_at: updatedAt }),
-          version: encodeHitVersion(doc),
-          attributes: doc._source[type],
-          references: doc._source.references || [],
-          migrationVersion: doc._source.migrationVersion,
-        };
+        // @ts-expect-error MultiGetHit._source is optional
+        return getSavedObjectFromSource(this._registry, type, id, doc);
       }),
     };
   }
@@ -968,7 +960,7 @@ export class SavedObjectsRepository {
 
     const namespace = normalizeNamespace(options.namespace);
 
-    const { body, statusCode } = await this.client.get<GetResponse<SavedObjectsRawDocSource>>(
+    const { body, statusCode } = await this.client.get<SavedObjectsRawDocSource>(
       {
         id: this._serializer.generateRawId(namespace, type, id),
         index: this.getIndexForType(type),
@@ -976,9 +968,12 @@ export class SavedObjectsRepository {
       { ignore: [404] }
     );
 
-    const docNotFound = body.found === false;
     const indexNotFound = statusCode === 404;
-    if (docNotFound || indexNotFound || !this.rawDocExistsInNamespace(body, namespace)) {
+    if (
+      !isFoundGetResponse(body) ||
+      indexNotFound ||
+      !this.rawDocExistsInNamespace(body, namespace)
+    ) {
       // see "404s from missing index" above
       throw SavedObjectsErrorHelpers.createGenericNotFoundError(type, id);
     }
@@ -1042,7 +1037,7 @@ export class SavedObjectsRepository {
       ...(Array.isArray(references) && { references }),
     };
 
-    const { body, statusCode } = await this.client.update(
+    const { body, statusCode } = await this.client.update<SavedObjectsRawDocSource>(
       {
         id: this._serializer.generateRawId(namespace, type, id),
         index: this.getIndexForType(type),
@@ -1062,11 +1057,11 @@ export class SavedObjectsRepository {
       throw SavedObjectsErrorHelpers.createGenericNotFoundError(type, id);
     }
 
-    const { originId } = body.get._source;
-    let namespaces = [];
+    const { originId } = body.get?._source ?? {};
+    let namespaces: string[] = [];
     if (!this._registry.isNamespaceAgnostic(type)) {
-      namespaces = body.get._source.namespaces ?? [
-        SavedObjectsUtils.namespaceIdToString(body.get._source.namespace),
+      namespaces = body.get?._source.namespaces ?? [
+        SavedObjectsUtils.namespaceIdToString(body.get?._source.namespace),
       ];
     }
 
@@ -1074,7 +1069,6 @@ export class SavedObjectsRepository {
       id,
       type,
       updated_at: time,
-      // @ts-expect-error update doesn't have _seq_no, _primary_term as Record<string, any> / any in LP
       version: encodeHitVersion(body),
       namespaces,
       ...(originId && { originId }),
@@ -1368,9 +1362,10 @@ export class SavedObjectsRepository {
           const actualResult = indexFound
             ? bulkGetResponse?.body.docs[opensearchRequestIndex]
             : undefined;
-          const docFound = indexFound && actualResult.found === true;
+          const docFound = indexFound && actualResult?.found === true;
           if (
             !docFound ||
+            // @ts-expect-error MultiGetHit is incorrectly missing _id, _source
             !this.rawDocExistsInNamespace(actualResult, getNamespaceId(objectNamespace))
           ) {
             return {
@@ -1382,9 +1377,12 @@ export class SavedObjectsRepository {
               },
             };
           }
-          namespaces = actualResult._source.namespaces ?? [
-            SavedObjectsUtils.namespaceIdToString(actualResult._source.namespace),
+          // @ts-expect-error MultiGetHit is incorrectly missing _id, _source
+          namespaces = actualResult!._source.namespaces ?? [
+            // @ts-expect-error MultiGetHit is incorrectly missing _id, _source
+            SavedObjectsUtils.namespaceIdToString(actualResult!._source.namespace),
           ];
+          // @ts-expect-error MultiGetHit is incorrectly missing _id, _source
           versionProperties = getExpectedVersionProperties(version, actualResult);
         } else {
           if (this._registry.isSingleNamespace(type)) {
@@ -1439,7 +1437,7 @@ export class SavedObjectsRepository {
           documentToSave,
           opensearchRequestIndex,
         } = expectedResult.value;
-        const response = bulkUpdateResponse?.body.items[opensearchRequestIndex];
+        const response = bulkUpdateResponse?.body.items[opensearchRequestIndex] ?? {};
         // When a bulk update operation is completed, any fields specified in `_sourceIncludes` will be found in the "get" value of the
         // returned object. We need to retrieve the `originId` if it exists so we can return it to the consumer.
         const { error, _seq_no: seqNo, _primary_term: primaryTerm, get } = Object.values(
@@ -1522,7 +1520,7 @@ export class SavedObjectsRepository {
 
     const raw = this._serializer.savedObjectToRaw(migrated as SavedObjectSanitizedDoc);
 
-    const { body } = await this.client.update({
+    const { body } = await this.client.update<SavedObjectsRawDocSource>({
       id: raw._id,
       index: this.getIndexForType(type),
       refresh,
@@ -1550,17 +1548,16 @@ export class SavedObjectsRepository {
       },
     });
 
-    const { originId } = body.get._source;
+    const { originId } = body.get?._source ?? {};
     return {
       id,
       type,
       ...(savedObjectNamespaces && { namespaces: savedObjectNamespaces }),
       ...(originId && { originId }),
       updated_at: time,
-      references: body.get._source.references,
-      // @ts-expect-error
+      references: body.get?._source.references ?? [],
       version: encodeHitVersion(body),
-      attributes: body.get._source[type],
+      attributes: body.get?._source[type],
     };
   }
 
@@ -1605,7 +1602,7 @@ export class SavedObjectsRepository {
    * WARNING: This should only be used for documents that were retrieved from OpenSearch. Otherwise, the guarantees of the document ID
    * format mentioned above do not apply.
    */
-  private rawDocExistsInNamespace(raw: SavedObjectsRawDoc, namespace?: string) {
+  private rawDocExistsInNamespace(raw: SavedObjectsRawDoc, namespace: string | undefined) {
     const rawDocType = raw._source.type;
 
     // if the type is namespace isolated, or namespace agnostic, we can continue to rely on the guarantees
@@ -1638,7 +1635,7 @@ export class SavedObjectsRepository {
       throw new Error(`Cannot make preflight get request for non-multi-namespace type '${type}'.`);
     }
 
-    const { body, statusCode } = await this.client.get<GetResponse<SavedObjectsRawDocSource>>(
+    const { body, statusCode } = await this.client.get<SavedObjectsRawDocSource>(
       {
         id: this._serializer.generateRawId(undefined, type, id),
         index: this.getIndexForType(type),
@@ -1649,8 +1646,7 @@ export class SavedObjectsRepository {
     );
 
     const indexFound = statusCode !== 404;
-    const docFound = indexFound && body.found === true;
-    if (docFound) {
+    if (indexFound && isFoundGetResponse(body)) {
       if (!this.rawDocExistsInNamespace(body, namespace)) {
         throw SavedObjectsErrorHelpers.createConflictError(type, id);
       }
@@ -1675,7 +1671,7 @@ export class SavedObjectsRepository {
     }
 
     const rawId = this._serializer.generateRawId(undefined, type, id);
-    const { body, statusCode } = await this.client.get<GetResponse<SavedObjectsRawDocSource>>(
+    const { body, statusCode } = await this.client.get<SavedObjectsRawDocSource>(
       {
         id: rawId,
         index: this.getIndexForType(type),
@@ -1684,11 +1680,14 @@ export class SavedObjectsRepository {
     );
 
     const indexFound = statusCode !== 404;
-    const docFound = indexFound && body.found === true;
-    if (!docFound || !this.rawDocExistsInNamespace(body, namespace)) {
+    if (
+      !indexFound ||
+      !isFoundGetResponse(body) ||
+      !this.rawDocExistsInNamespace(body, namespace)
+    ) {
       throw SavedObjectsErrorHelpers.createGenericNotFoundError(type, id);
     }
-    return body as SavedObjectsRawDoc;
+    return body;
   }
 }
 
@@ -1741,6 +1740,44 @@ function getSavedObjectNamespaces(
   return [SavedObjectsUtils.namespaceIdToString(namespace)];
 }
 
+/**
+ * Gets a saved object from a raw OpenSearch document.
+ *
+ * @param registry Registry which holds the registered saved object types information.
+ * @param type The type of the saved object.
+ * @param id The ID of the saved object.
+ * @param doc Doc contains _source and optional _seq_no and _primary_term.
+ *
+ * @internal
+ */
+function getSavedObjectFromSource<T>(
+  registry: ISavedObjectTypeRegistry,
+  type: string,
+  id: string,
+  doc: { _seq_no?: number; _primary_term?: number; _source: SavedObjectsRawDocSource }
+): SavedObject<T> {
+  const { originId, updated_at: updatedAt } = doc._source;
+
+  let namespaces: string[] = [];
+  if (!registry.isNamespaceAgnostic(type)) {
+    namespaces = doc._source.namespaces ?? [
+      SavedObjectsUtils.namespaceIdToString(doc._source.namespace),
+    ];
+  }
+
+  return {
+    id,
+    type,
+    namespaces,
+    ...(originId && { originId }),
+    ...(updatedAt && { updated_at: updatedAt }),
+    version: encodeHitVersion(doc),
+    attributes: doc._source[type],
+    references: doc._source.references || [],
+    migrationVersion: doc._source.migrationVersion,
+  };
+}
+
 /**
  * Ensure that a namespace is always in its namespace ID representation.
  * This allows `'default'` to be used interchangeably with `undefined`.
@@ -1761,3 +1798,18 @@ const normalizeNamespace = (namespace?: string) => {
 const errorContent = (error: DecoratedError) => error.output.payload;
 
 const unique = (array: string[]) => [...new Set(array)];
+
+/**
+ * Type and type guard function for converting a possibly not existant doc to an existant doc.
+ */
+type GetResponseFound<TDocument = unknown> = opensearchtypes.GetResponse<TDocument> &
+  Required<
+    Pick<
+      opensearchtypes.GetResponse<TDocument>,
+      '_primary_term' | '_seq_no' | '_version' | '_source'
+    >
+  >;
+
+const isFoundGetResponse = <TDocument = unknown>(
+  doc: opensearchtypes.GetResponse<TDocument>
+): doc is GetResponseFound<TDocument> => doc.found;
diff --git a/src/core/server/saved_objects/service/lib/search_dsl/sorting_params.test.ts b/src/core/server/saved_objects/service/lib/search_dsl/sorting_params.test.ts
index 10038d532143..afef66e5a2f7 100644
--- a/src/core/server/saved_objects/service/lib/search_dsl/sorting_params.test.ts
+++ b/src/core/server/saved_objects/service/lib/search_dsl/sorting_params.test.ts
@@ -74,7 +74,7 @@ const MAPPINGS = {
       },
     },
   },
-};
+} as const;
 
 describe('searchDsl/getSortParams', () => {
   describe('type, no sortField', () => {
diff --git a/src/core/server/saved_objects/version/encode_hit_version.ts b/src/core/server/saved_objects/version/encode_hit_version.ts
index 4de5fc4dc99a..f82df69a8153 100644
--- a/src/core/server/saved_objects/version/encode_hit_version.ts
+++ b/src/core/server/saved_objects/version/encode_hit_version.ts
@@ -31,6 +31,6 @@ import { encodeVersion } from './encode_version';
  * Helper for encoding a version from a "hit" (hits.hits[#] from _search) or
  * "doc" (body from GET, update, etc) object
  */
-export function encodeHitVersion(response: { _seq_no: number; _primary_term: number }) {
+export function encodeHitVersion(response: { _seq_no?: number; _primary_term?: number }) {
   return encodeVersion(response._seq_no, response._primary_term);
 }
diff --git a/src/core/server/saved_objects/version/encode_version.ts b/src/core/server/saved_objects/version/encode_version.ts
index cb9a232dd8f7..c56fd6c9d818 100644
--- a/src/core/server/saved_objects/version/encode_version.ts
+++ b/src/core/server/saved_objects/version/encode_version.ts
@@ -32,7 +32,7 @@ import { encodeBase64 } from './base64';
  * that can be used in the saved object API in place of numeric
  * version numbers
  */
-export function encodeVersion(seqNo: number, primaryTerm: number) {
+export function encodeVersion(seqNo?: number, primaryTerm?: number) {
   if (!Number.isInteger(primaryTerm)) {
     throw new TypeError('_primary_term from opensearch must be an integer');
   }
diff --git a/src/core/server/server.api.md b/src/core/server/server.api.md
index ea28b2e51648..6061f78557b5 100644
--- a/src/core/server/server.api.md
+++ b/src/core/server/server.api.md
@@ -2060,38 +2060,6 @@ export interface SavedObjectsClientWrapperOptions {
     typeRegistry: ISavedObjectTypeRegistry;
 }
 
-// @public
-export interface SavedObjectsComplexFieldMapping {
-    // (undocumented)
-    doc_values?: boolean;
-    dynamic?: false | 'strict';
-    // (undocumented)
-    enabled?: boolean;
-    // (undocumented)
-    properties: SavedObjectsMappingProperties;
-    // (undocumented)
-    type?: string;
-}
-
-// @public
-export interface SavedObjectsCoreFieldMapping {
-    // (undocumented)
-    doc_values?: boolean;
-    // (undocumented)
-    fields?: {
-        [subfield: string]: {
-            type: string;
-            ignore_above?: number;
-        };
-    };
-    // (undocumented)
-    index?: boolean;
-    // (undocumented)
-    null_value?: number | boolean | string;
-    // (undocumented)
-    type: string;
-}
-
 // @public (undocumented)
 export interface SavedObjectsCreateOptions extends SavedObjectsBaseOptions {
     id?: string;
@@ -2210,7 +2178,9 @@ export interface SavedObjectsExportResultDetails {
 }
 
 // @public
-export type SavedObjectsFieldMapping = SavedObjectsCoreFieldMapping | SavedObjectsComplexFieldMapping;
+export type SavedObjectsFieldMapping = opensearchtypes.MappingProperty & {
+    dynamic?: false | 'strict';
+};
 
 // @public (undocumented)
 export interface SavedObjectsFindOptions {