diff --git a/.github/workflows/preview-apk.yml b/.github/workflows/preview-apk.yml
index cc509841f4..e297073fe2 100644
--- a/.github/workflows/preview-apk.yml
+++ b/.github/workflows/preview-apk.yml
@@ -49,7 +49,7 @@ jobs:
         run: ./gradlew --no-daemon assembleGplayDebug
 
       - name: Upload APK
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: app-preview.apk
           path: 'build/outputs/apk/gplay/debug/*.apk'
diff --git a/src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java b/src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java
index 47b93b4d80..3415596633 100644
--- a/src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java
+++ b/src/main/java/org/thoughtcrime/securesms/service/FetchForegroundService.java
@@ -49,12 +49,14 @@ public static void start(Context context) {
         // The background fetch was successful, but we need to wait until all events were processed.
         // After all events were processed, we will get DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE,
         // and stop() will be called.
-        while (fetchingSynchronously) {
-          try {
-            // The `wait()` needs to be enclosed in a while loop because there may be
-            // "spurious wake-ups", i.e. `wait()` may return even though `notifyAll()` wasn't called.
-            STOP_NOTIFIER.wait();
-          } catch (InterruptedException ex) { }
+        synchronized (STOP_NOTIFIER) {
+          while (fetchingSynchronously) {
+            try {
+              // The `wait()` needs to be enclosed in a while loop because there may be
+              // "spurious wake-ups", i.e. `wait()` may return even though `notifyAll()` wasn't called.
+              STOP_NOTIFIER.wait();
+            } catch (InterruptedException ex) {}
+          }
         }
       }
     }
@@ -63,7 +65,9 @@ public static void start(Context context) {
   public static void stop(Context context) {
     if (fetchingSynchronously) {
       fetchingSynchronously = false;
-      STOP_NOTIFIER.notifyAll();
+      synchronized (STOP_NOTIFIER) {
+        STOP_NOTIFIER.notifyAll();
+      }
     }
 
     synchronized (SERVICE_LOCK) {