A fetch request on the page that sets the cache: "no-cache" will result in a network error when it is fetched by a Service Worker. The error that is thrown looks like this: TypeError: Request header field Cache-Control is not allowed by Access-Control-Allow-Headers I implemented a simple test page that reproduces the issue here: https://testjanos.app.baqend.com/ The test page registers a simple Service Worker which listens to fetch requests and tries to fetch them. It also includes the following script tag: <script> let options = { method: "POST", cache: "no-cache", mode: "cors", body: '{"weather":true}' }; fetch("https://dcinfos-cache.abtasty.com/v1/geoip", options); </script> Ways to reproduce: 1. Go to https://testjanos.app.baqend.com/ 2. Open Service Workers view (Developer -> Service Workers) 3. Refresh the page 4. Observe that resource https://dcinfos-cache.abtasty.com/v1/geoip could not be fetched due to above error (error prited to the Service Worker console) Is there any fix for this issue?