Refused to create a worker because it violates the following Content Security Policy directive: worker-src

[cmacdonnacha]

Keep seeing this error in the console. MSW still runs, but would like to find the source of the issue.

Refused to create a worker from 'http://localhost:3000/mockServiceWorker.js' because it violates the following Content Security Policy directive: "worker-src blob:"."

[kettanaito]

Hi, @cmacdonnacha.

Why is this happening?

It looks like your server has a strict Content-Security-Policy defined that only allows certain origins for worker-src. To my best knowledge, worker-src blob: translates to: only allow installing workers at the blob: identifier. Since MSW worker is installed using the http: scheme, it violates the set security policy, raising the error you see.

How to resolve it?

First, see if you can adjust the Content-Security-Policy values on your server. Those make sense in production but you may have a looser set for development to allow tools like MSW.

If you don't own the server or cannot adjust the said policy, you can look into browser-level whitelisting rules for that. There's nothing we can do on MSW side since it isn't the library's issue.

[cmacdonnacha]

Thanks @kettanaito