diff --git a/src/platform/web/docroot/sw.js b/src/platform/web/docroot/sw.js
index 21fdf2d2..9b5da128 100644
--- a/src/platform/web/docroot/sw.js
+++ b/src/platform/web/docroot/sw.js
@@ -68,8 +68,10 @@ async function purgeOldCaches() {
     }
 }
 
-self.addEventListener('fetch', (event) => {
-    if (event.request.url.indexOf("upload") !== -1) {
+self.addEventListener('fetch', async (event) => {
+    if (event.request.method === "POST" &&
+        (await event.request.blob()).type !== "application/json" &&
+        event.request.body) {
         return;
     }
     event.respondWith(handleRequest(event.request));