diff --git a/services/usage/java/com/android/server/usage/UsageStatsService.java b/services/usage/java/com/android/server/usage/UsageStatsService.java
index 27c383c..bf46154 100644
--- a/services/usage/java/com/android/server/usage/UsageStatsService.java
+++ b/services/usage/java/com/android/server/usage/UsageStatsService.java
@@ -113,6 +113,7 @@
 import com.android.server.IoThread;
 import com.android.server.LocalServices;
 import com.android.server.SystemService;
+import com.android.server.pm.UserManagerInternal;
 import com.android.server.usage.AppStandbyInternal.AppIdleStateChangeListener;
 import com.android.server.utils.AlarmQueue;
 
@@ -1063,6 +1064,18 @@
         synchronized (mReportedEvents) {
             LinkedList<Event> events = mReportedEvents.get(userId);
             if (events == null) {
+                // TODO (b/347644400): callers of this API should verify that the userId passed to
+                // this method exists - there is currently a known case where USER_ALL is passed
+                // here and it would be added to the queue, never to be flushed correctly. The logic
+                // below should only remain as a last-resort catch-all fix.
+                final UserManagerInternal umi = LocalServices.getService(UserManagerInternal.class);
+                if (umi == null || (umi != null && !umi.exists(userId))) {
+                    // The userId passed is a non-existent user so don't report the event.
+                    Slog.wtf(TAG, "Attempted to report event for non-existent user " + userId
+                            + " (" + event.mPackage + "/" + event.mClass
+                            + " eventType:" + event.mEventType + ")");
+                    return;
+                }
                 events = new LinkedList<>();
                 mReportedEvents.put(userId, events);
             }