diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 0904c8e71df22..f496a672e8d72 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -1817,7 +1817,8 @@ class ActivityStack<T extends StackWindowController> extends ConfigurationContai
             boolean behindFullscreenActivity = !stackShouldBeVisible;
             boolean resumeNextActivity = mStackSupervisor.isFocusedStack(this)
                     && (isInStackLocked(starting) == null);
-            final boolean isTopNotPinnedStack = getDisplay().isTopNotPinnedStack(this);
+            final boolean isTopNotPinnedStack =
+                    isAttached() && getDisplay().isTopNotPinnedStack(this);
             for (int taskNdx = mTaskHistory.size() - 1; taskNdx >= 0; --taskNdx) {
                 final TaskRecord task = mTaskHistory.get(taskNdx);
                 final ArrayList<ActivityRecord> activities = task.mActivities;