--- a/services/sync/modules/policies.js
+++ b/services/sync/modules/policies.js
@@ -396,16 +396,25 @@ SyncScheduler.prototype = {
       this._log.debug("Not initiating sync: Login status is " + Status.login);
 
       // If we're not syncing now, we need to schedule the next one.
       this._log.trace("Scheduling a sync at MASTER_PASSWORD_LOCKED_RETRY_INTERVAL");
       this.scheduleAtInterval(MASTER_PASSWORD_LOCKED_RETRY_INTERVAL);
       return;
     }
 
+    try {
+      Async.checkAppReady()
+    } catch (ex) {
+      if (Async.isShutdownException(ex)) {
+        this._log.debug("Not initiating sync: app is shutting down");
+        return;
+      }
+      throw ex;
+    }
     Utils.nextTick(this.service.sync, this.service);
   },
 
   /**
    * Set a timer for the next sync
    */
   scheduleNextSync: function scheduleNextSync(interval) {
     // If no interval was specified, use the current sync interval.