diff --git a/services/core/java/com/android/server/wm/ActivityStarter.java b/services/core/java/com/android/server/wm/ActivityStarter.java
index 003268b33cdc0..602e4160a679c 100644
--- a/services/core/java/com/android/server/wm/ActivityStarter.java
+++ b/services/core/java/com/android/server/wm/ActivityStarter.java
@@ -1935,6 +1935,14 @@ class ActivityStarter {
         } else if (mSourceRecord != null) {
             return mSourceRecord.getTask();
         } else if (mInTask != null) {
+            // The task is specified from AppTaskImpl, so it may not be attached yet.
+            if (!mInTask.isAttached()) {
+                // Clear reuse task so it can find a proper parent to add the task.
+                if (mReuseTask == mInTask) {
+                    mReuseTask = null;
+                }
+                return getOrCreateRootTask(mStartActivity, mLaunchFlags, mInTask, mOptions);
+            }
             return mInTask;
         } else {
             final Task rootTask = getOrCreateRootTask(mStartActivity, mLaunchFlags, null /* task */,
diff --git a/services/core/java/com/android/server/wm/AppTaskImpl.java b/services/core/java/com/android/server/wm/AppTaskImpl.java
index 22a2c41ca5f32..6e46fa6b67d0d 100644
--- a/services/core/java/com/android/server/wm/AppTaskImpl.java
+++ b/services/core/java/com/android/server/wm/AppTaskImpl.java
@@ -26,6 +26,8 @@ import android.content.Intent;
 import android.os.Binder;
 import android.os.Bundle;
 import android.os.IBinder;
+import android.os.Parcel;
+import android.os.RemoteException;
 import android.os.UserHandle;
 
 /**
@@ -53,6 +55,16 @@ class AppTaskImpl extends IAppTask.Stub {
         }
     }
 
+    @Override
+    public boolean onTransact(int code, Parcel data, Parcel reply, int flags)
+            throws RemoteException {
+        try {
+            return super.onTransact(code, data, reply, flags);
+        } catch (RuntimeException e) {
+            throw ActivityTaskManagerService.logAndRethrowRuntimeExceptionOnTransact(TAG, e);
+        }
+    }
+
     @Override
     public void finishAndRemoveTask() {
         checkCaller();
diff --git a/services/tests/wmtests/src/com/android/server/wm/ActivityStarterTests.java b/services/tests/wmtests/src/com/android/server/wm/ActivityStarterTests.java
index 9902e83c3648d..908de34352c99 100644
--- a/services/tests/wmtests/src/com/android/server/wm/ActivityStarterTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/ActivityStarterTests.java
@@ -1139,18 +1139,8 @@ public class ActivityStarterTests extends WindowTestsBase {
                 true /* createdByOrganizer */);
         sourceRecord.getTask().addChild(taskFragment, POSITION_TOP);
 
-        starter.startActivityInner(
-                /* r */targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */true,
-                /* options */null,
-                /* inTask */null,
-                /* inTaskFragment */ taskFragment,
-                /* restrictedBgActivity */false,
-                /* intentGrants */null);
+        startActivityInner(starter, targetRecord, sourceRecord, null /* options */,
+                null /* inTask */, taskFragment);
 
         assertFalse(taskFragment.hasChild());
     }
@@ -1167,18 +1157,8 @@ public class ActivityStarterTests extends WindowTestsBase {
         taskFragment.setTaskFragmentOrganizer(mock(TaskFragmentOrganizerToken.class), SYSTEM_UID,
                 "system_uid");
 
-        starter.startActivityInner(
-                /* r */targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */true,
-                /* options */null,
-                /* inTask */null,
-                /* inTaskFragment */ taskFragment,
-                /* restrictedBgActivity */false,
-                /* intentGrants */null);
+        startActivityInner(starter, targetRecord, sourceRecord, null /* options */,
+                null /* inTask */, taskFragment);
 
         assertTrue(taskFragment.hasChild());
     }
@@ -1195,18 +1175,8 @@ public class ActivityStarterTests extends WindowTestsBase {
         taskFragment.setTaskFragmentOrganizer(mock(TaskFragmentOrganizerToken.class),
                 targetRecord.getUid(), "test_process_name");
 
-        starter.startActivityInner(
-                /* r */targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */true,
-                /* options */null,
-                /* inTask */null,
-                /* inTaskFragment */ taskFragment,
-                /* restrictedBgActivity */false,
-                /* intentGrants */null);
+        startActivityInner(starter, targetRecord, sourceRecord, null /* options */,
+                null /* inTask */, taskFragment);
 
         assertTrue(taskFragment.hasChild());
     }
@@ -1231,18 +1201,8 @@ public class ActivityStarterTests extends WindowTestsBase {
         doReturn(true).when(signingDetails).hasAncestorOrSelfWithDigest(any());
         doReturn(signingDetails).when(androidPackage).getSigningDetails();
 
-        starter.startActivityInner(
-                /* r */targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */true,
-                /* options */null,
-                /* inTask */null,
-                /* inTaskFragment */ taskFragment,
-                /* restrictedBgActivity */false,
-                /* intentGrants */null);
+        startActivityInner(starter, targetRecord, sourceRecord, null /* options */,
+                null /* inTask */, taskFragment);
 
         assertTrue(taskFragment.hasChild());
     }
@@ -1258,22 +1218,29 @@ public class ActivityStarterTests extends WindowTestsBase {
 
         targetRecord.info.flags |= ActivityInfo.FLAG_ALLOW_UNTRUSTED_ACTIVITY_EMBEDDING;
 
-        starter.startActivityInner(
-                /* r */targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */true,
-                /* options */null,
-                /* inTask */null,
-                /* inTaskFragment */ taskFragment,
-                /* restrictedBgActivity */false,
-                /* intentGrants */null);
+        startActivityInner(starter, targetRecord, sourceRecord, null /* options */,
+                null /* inTask */, taskFragment);
 
         assertTrue(taskFragment.hasChild());
     }
 
+    @Test
+    public void testStartActivityInner_inTask() {
+        final ActivityStarter starter = prepareStarter(0, false);
+        // Simulate an app uses AppTask to create a non-attached task, and then it requests to
+        // start activity in the task.
+        final Task inTask = new TaskBuilder(mSupervisor).setTaskDisplayArea(null).setTaskId(123)
+                .build();
+        inTask.inRecents = true;
+        assertFalse(inTask.isAttached());
+        final ActivityRecord target = new ActivityBuilder(mAtm).build();
+        startActivityInner(starter, target, null /* source */, null /* options */, inTask,
+                null /* inTaskFragment */);
+
+        assertTrue(inTask.isAttached());
+        assertEquals(inTask, target.getTask());
+    }
+
     @Test
     public void testLaunchCookie_newAndExistingTask() {
         final ActivityStarter starter = prepareStarter(0, false);
@@ -1322,21 +1289,20 @@ public class ActivityStarterTests extends WindowTestsBase {
 
         // Start the target launch-into-pip activity from a source
         final ActivityRecord sourceRecord = new ActivityBuilder(mAtm).setCreateTask(true).build();
-        starter.startActivityInner(
-                /* r */ targetRecord,
-                /* sourceRecord */ sourceRecord,
-                /* voiceSession */ null,
-                /* voiceInteractor */ null,
-                /* startFlags */ 0,
-                /* doResume */ true,
-                /* options */ opts,
-                /* inTask */ null,
-                /* inTaskFragment */ null,
-                /* restrictedBgActivity */ false,
-                /* intentGrants */ null);
+        startActivityInner(starter, targetRecord, sourceRecord, opts,
+                null /* inTask */, null /* inTaskFragment */);
 
         // Verify the ActivityRecord#getLaunchIntoPipHostActivity points to sourceRecord.
         assertThat(targetRecord.getLaunchIntoPipHostActivity()).isNotNull();
         assertEquals(targetRecord.getLaunchIntoPipHostActivity(), sourceRecord);
     }
+
+    private static void startActivityInner(ActivityStarter starter, ActivityRecord target,
+            ActivityRecord source, ActivityOptions options, Task inTask,
+            TaskFragment inTaskFragment) {
+        starter.startActivityInner(target, source, null /* voiceSession */,
+                null /* voiceInteractor */, 0 /* startFlags */, true /* doResume */,
+                options, inTask, inTaskFragment, false /* restrictedBgActivity */,
+                null /* intentGrants */);
+    }
 }