diff --git a/ui/media/js/engine.js b/ui/media/js/engine.js
index ed5ed2d5..11d88e3b 100644
--- a/ui/media/js/engine.js
+++ b/ui/media/js/engine.js
@@ -437,7 +437,7 @@
          * @memberof Task
          */
         async post(url, timeout=-1) {
-	    if (typeof pauseClient != 'undefined' && pauseClient===true) {
+	    if (typeof pauseClient != 'undefined' && pauseClient===true && typeof resumeClient === 'function') {
 	        await resumeClient()
 	    }
             if(this.status !== TaskStatus.init && this.status !== TaskStatus.pending) {