Calling fetch function for push notifications in service worker causes CORS error

[Julien Phan]

Hi, I have an app that calls a api fetch call for push notifications in the service worker and it returns the follow error:
Access to fetch at 'ressource from server' from origin 'domain' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

Operating System: Windows
Node Version: latest
web-push Version: latest

Please select any browsers that you are experiencing problems with:

• Chrome
• Firefox
• Edge

Problem

As mentioned before, the issue is that we are getting a CORS error, but other fetch functions called by the service worker works fine. I was wondering if the vapid keys might have anything to do with it ? On top of this, I only get this issue on my deployed app using vercel and not locally. I've tried to add the following lines to my server file:
app.use((req, res, next) => {
res.setHeader("Access-Control-Allow-Origin", "*");
next();
});
but unfortunately I still get the error. Since I am not getting an error with my other fetch calls, I was wondering maybe web-push has specifics to setup or any of the sort. Any help would be appreciated!

Features Used

• [ x] VAPID Support
• [x ] GCM API Key
• [ x] Sending with Payload

[ilyahorski]

Hi! Same for me. I'm encountering a CORS error on a Vercel deployment client after I added web-push logic to my Heroku socket server. I also tried to allow all domains on the client and server in the headers, but this did not work. Were you able to find a solution to the problem?