diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidBinary.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidBinary.java
index 1ed8538c60e599..3799714ea24623 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidBinary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidBinary.java
@@ -1815,7 +1815,7 @@ static Artifact createMainDexListAction(
       Artifact jar,
       @Nullable Artifact mainDexProguardSpec,
       @Nullable Artifact proguardOutputMap)
-      throws InterruptedException {
+      throws InterruptedException, RuleErrorException {
     AndroidSdkProvider sdk = AndroidSdkProvider.fromRuleContext(ruleContext);
     // Create the main dex classes list.
     Artifact mainDexList = AndroidBinary.getDxArtifact(ruleContext, "main_dex_list.txt");
@@ -1841,6 +1841,11 @@ static Artifact createMainDexListAction(
     // legacy_main_dex_list_generator is provided, use that tool instead.
     // TODO(b/147692286): Remove the old main-dex list generation that relied on ProGuard.
     if (legacyMainDexListGenerator == null) {
+      if (sdk.getShrinkedAndroidJar() == null) {
+        ruleContext.throwWithRuleError(
+            "In \"legacy\" multidex mode, either legacy_main_dex_list_generator or "
+                + "shrinked_android_jar must be set in the android_sdk.");
+      }
       // Process the input jar through Proguard into an intermediate, streamlined jar.
       Artifact strippedJar = AndroidBinary.getDxArtifact(ruleContext, "main_dex_intermediate.jar");
       SpawnAction.Builder streamlinedBuilder =
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidSdkProvider.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidSdkProvider.java
index df268c20c81b43..fc860b05add2ee 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidSdkProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidSdkProvider.java
@@ -54,7 +54,7 @@ public final class AndroidSdkProvider extends NativeInfo
   private final TransitiveInfoCollection aidlLib;
   private final Artifact androidJar;
   private final Artifact sourceProperties;
-  private final Artifact shrinkedAndroidJar;
+  @Nullable private final Artifact shrinkedAndroidJar;
   private final Artifact mainDexClasses;
   private final FilesToRunProvider adb;
   private final FilesToRunProvider dx;
@@ -75,7 +75,7 @@ public AndroidSdkProvider(
       @Nullable TransitiveInfoCollection aidlLib,
       Artifact androidJar,
       @Nullable Artifact sourceProperties,
-      Artifact shrinkedAndroidJar,
+      @Nullable Artifact shrinkedAndroidJar,
       Artifact mainDexClasses,
       FilesToRunProvider adb,
       FilesToRunProvider dx,
@@ -234,6 +234,7 @@ public Artifact getSourceProperties() {
   }
 
   @Override
+  @Nullable
   public Artifact getShrinkedAndroidJar() {
     return shrinkedAndroidJar;
   }
@@ -320,7 +321,7 @@ public AndroidSdkProvider createInfo(
         Object aidlLib,
         Artifact androidJar,
         Object sourceProperties,
-        Artifact shrinkedAndroidJar,
+        Object shrinkedAndroidJar,
         Artifact mainDexClasses,
         FilesToRunProvider adb,
         FilesToRunProvider dx,
@@ -341,7 +342,7 @@ public AndroidSdkProvider createInfo(
           fromNoneable(aidlLib, TransitiveInfoCollection.class),
           androidJar,
           fromNoneable(sourceProperties, Artifact.class),
-          shrinkedAndroidJar,
+          fromNoneable(shrinkedAndroidJar, Artifact.class),
           mainDexClasses,
           adb,
           dx,
diff --git a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/android/AndroidSdkProviderApi.java b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/android/AndroidSdkProviderApi.java
index f1d91f1df7d6f2..c25fabe5a92791 100644
--- a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/android/AndroidSdkProviderApi.java
+++ b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/android/AndroidSdkProviderApi.java
@@ -80,7 +80,13 @@ public interface AndroidSdkProviderApi<
   @Nullable
   FileT getSourceProperties();
 
-  @StarlarkMethod(name = "shrinked_android_jar", structField = true, doc = "", documented = false)
+  @StarlarkMethod(
+      name = "shrinked_android_jar",
+      structField = true,
+      doc = "",
+      documented = false,
+      allowReturnNones = true)
+  @Nullable
   FileT getShrinkedAndroidJar();
 
   @StarlarkMethod(name = "main_dex_classes", structField = true, doc = "", documented = false)
@@ -186,7 +192,11 @@ interface Provider<
               name = "shrinked_android_jar",
               doc = "An artifact of the shrunk Android Jar.",
               positional = true,
-              named = false),
+              named = false,
+              allowedTypes = {
+                @ParamType(type = FileApi.class),
+                @ParamType(type = NoneType.class),
+              }),
           @Param(
               name = "main_dex_classes",
               doc = "An artifact of the main dex classes.",
@@ -270,7 +280,7 @@ AndroidSdkProviderApi<FileT, FilesToRunProviderT, TransT> createInfo(
         Object aidlLib,
         FileT androidJar,
         Object sourceProperties,
-        FileT shrinkedAndroidJar,
+        Object shrinkedAndroidJar,
         FileT mainDexClasses,
         FilesToRunProviderT adb,
         FilesToRunProviderT dx,
diff --git a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/android/FakeAndroidSdkProvider.java b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/android/FakeAndroidSdkProvider.java
index f7caed4237fcc5..a65cd88c46dee0 100644
--- a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/android/FakeAndroidSdkProvider.java
+++ b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/android/FakeAndroidSdkProvider.java
@@ -53,6 +53,7 @@ public FileApi getSourceProperties() {
     return null;
   }
 
+  @Nullable
   @Override
   public FileApi getShrinkedAndroidJar() {
     return null;
@@ -144,7 +145,7 @@ public static class FakeProvider
             Object aidlLib,
             FileApi androidJar,
             Object sourceProperties,
-            FileApi shrinkedAndroidJar,
+            Object shrinkedAndroidJar,
             FileApi mainDexClasses,
             FilesToRunProviderApi<FileApi> adb,
             FilesToRunProviderApi<FileApi> dx,