diff --git a/chrome/content/zotero/xpcom/connector/server_connector.js b/chrome/content/zotero/xpcom/connector/server_connector.js
index c80293b25a..49a534a05b 100644
--- a/chrome/content/zotero/xpcom/connector/server_connector.js
+++ b/chrome/content/zotero/xpcom/connector/server_connector.js
@@ -1067,9 +1067,9 @@ Zotero.Server.Connector.DelaySync.prototype = {
 	supportedMethods: ["POST"],
 	permitBookmarklet: true,
 	
-	init: async function (requestData) {
+	init: function (requestData) {
 		Zotero.Sync.Runner.delaySync(10000);
-		return [204];
+		return 204;
 	}
 };
 
diff --git a/chrome/content/zotero/xpcom/connector/server_connectorIntegration.js b/chrome/content/zotero/xpcom/connector/server_connectorIntegration.js
index 3cc8571523..a1328db0cc 100644
--- a/chrome/content/zotero/xpcom/connector/server_connectorIntegration.js
+++ b/chrome/content/zotero/xpcom/connector/server_connectorIntegration.js
@@ -82,7 +82,8 @@ Zotero.Server.Endpoints['/connector/sendToBack'].prototype = {
 	supportedMethods: ["POST", "GET"],
 	supportedDataTypes: ["application/json"],
 	permitBookmarklet: true,
-	init: function() {
+	init: function (requestData) {
 		Zotero.Utilities.Internal.sendToBack();
+		return 200;
 	},
 };