React website behaving differently in Brave (XMLHttpRequest preflight)

I’m having a curious issue with a ReactJS (built with create-react-app project). Part of the App’s functionality is to use the Amazon AWS React SDK to interact with some AWS services. This is done using the promises feature of the AWS SDK (i.e. I have a small chain of AWS promises : svc1.then.svc2.then.svc3.then.displayresult’)

This all works perfectly well on all common browsers EXCEPT Brave:

  • Firefox : Works OK
  • Safari: Works OK
  • Edge: Works OK
  • Chrome: Works OK
  • Brave: Fails

Given Brave is closely related to Chrome, I’m not entirely sure what’s going on here ?

Also given 99% of browsers work and only Brave does not, I am also not sure where (or how !) to start troubleshooting?

My code is not complex, as I said, its a simple and short chain of AWS SDK calls which happen as a result of an onClick triggered by a user hitting a submit button on a form.

No, I can’t share anything. Its an internal site, quite late into its development, so a public version would be difficult. Yes, I know this is frustrating in terms of support, but I remind you I am only looking for general hints and ideas from people who may have encountered this (and indeed the Brave developers who may know more about the “internals” difference between Brave and Chrome).

The only thing I can share is my console log extract in Brave:

Access to XMLHttpRequest at ‘’ from origin ‘http://’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: Redirect is not allowed for a preflight request.

But again I don’t see how CORS makes sense when I have put in place CORS measures and it all works on other browsers ?

Hi @foobar,

It’s a known issue. It should be fixed in the next hotfix


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