diff --git a/chrome/content/zotero/xpcom/storage/queue.js b/chrome/content/zotero/xpcom/storage/queue.js
index 941e79e50..5b4962026 100644
--- a/chrome/content/zotero/xpcom/storage/queue.js
+++ b/chrome/content/zotero/xpcom/storage/queue.js
@@ -230,7 +230,12 @@ Zotero.Sync.Storage.Queue.prototype.start = function () {
 	// The queue manager needs to know what queues were running in the
 	// current session
 	Zotero.Sync.Storage.QueueManager.addCurrentQueue(this);
-	this.advance();
+	
+	var self = this;
+	setTimeout(function () {
+		self.advance();
+	}, 0);
+	
 	return this._deferred.promise;
 }
 
diff --git a/chrome/content/zotero/xpcom/storage/webdav.js b/chrome/content/zotero/xpcom/storage/webdav.js
index a762079bd..108a4eccc 100644
--- a/chrome/content/zotero/xpcom/storage/webdav.js
+++ b/chrome/content/zotero/xpcom/storage/webdav.js
@@ -957,7 +957,7 @@ Zotero.Sync.Storage.WebDAV = (function () {
 	
 	obj._uploadFile = function (request) {
 		var deferred = Q.defer();
-		Zotero.Sync.Storage.createUploadFile(
+		var created = Zotero.Sync.Storage.createUploadFile(
 			request,
 			function (data) {
 				deferred.resolve(
@@ -967,6 +967,9 @@ Zotero.Sync.Storage.WebDAV = (function () {
 				);
 			}
 		);
+		if (!created) {
+			return Q(false);
+		}
 		return deferred.promise;
 	};