diff --git a/packages/react-scripts/template/src/serviceWorker.js b/packages/react-scripts/template/src/serviceWorker.js
index 8859a0c6b2094624b51600afadbaf46c67987cc1..a0153cb4c47159b087c75f01baf94f00b305c2b9 100644
--- a/packages/react-scripts/template/src/serviceWorker.js
+++ b/packages/react-scripts/template/src/serviceWorker.js
@@ -78,7 +78,7 @@ function registerValidSW(swUrl, config) {
               console.log('Content is cached for offline use.');
 
               // Execute callback
-              if (config.onSuccess) {
+              if (config && config.onSuccess) {
                 config.onSuccess(registration);
               }
             }