If loading a workflow without a version by instance id - use that ins…

…tance.

lib/galaxy/model/__init__.py

@@ -7748,6 +7748,15 @@ def get_internal_version(self, version):
             raise galaxy.exceptions.RequestParameterInvalidException("Version does not exist")
         return list(reversed(self.workflows))[version]
 
+    def get_internal_version_by_id(self, workflow_instance_id: int):
+        sa_session = object_session(self)
+        workflow = sa_session.get(Workflow, workflow_instance_id)
+        if not workflow:
+            raise galaxy.exceptions.ObjectNotFound()
+        elif workflow.stored_workflow != self:
+            raise galaxy.exceptions.RequestParameterInvalidException()
+        return workflow
+
     def version_of(self, workflow):
         for version, workflow_instance in enumerate(reversed(self.workflows)):
             if workflow_instance.id == workflow.id:

lib/galaxy/webapps/galaxy/services/workflows.py

@@ -131,7 +131,10 @@ def invoke_workflow(
         by_stored_id = not payload.instance
         stored_workflow = self._workflows_manager.get_stored_accessible_workflow(trans, workflow_id, by_stored_id)
         version = payload.version
-        workflow = stored_workflow.get_internal_version(version)
+        if version is None and payload.instance:
+            workflow = stored_workflow.get_internal_version_by_id(workflow_id)
+        else:
+            workflow = stored_workflow.get_internal_version(version)
         run_configs = build_workflow_run_configs(trans, workflow, payload.model_dump(exclude_unset=True))
         is_batch = payload.batch
         if not is_batch and len(run_configs) != 1: