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CORS-Preflight request fails on mTLS-secured connection

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Hey, I am currently working on an application where I want to upload files to a server using mtls via a webapp. The upload goes to another url and server than the one where the webapp is served from. If I test the file uploading without mTLS, it succeeds, and with mTLS enabled it also works in chromium, but in Firefox I get the following error: "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at <url> (Reason: CORS request did not succeed). Status code: (null)." on the `OPTIONS` request before the `PUT` is done. The client and the server both have a certificate from a custom CA, which I imported into firefox, along with the private key. Does someone know what the issue here might be? I am suspecting that there is some problem with firefox loading the user certificate on the preflight request?

Hey, I am currently working on an application where I want to upload files to a server using mtls via a webapp. The upload goes to another url and server than the one where the webapp is served from. If I test the file uploading without mTLS, it succeeds, and with mTLS enabled it also works in chromium, but in Firefox I get the following error: "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at <url> (Reason: CORS request did not succeed). Status code: (null)." on the `OPTIONS` request before the `PUT` is done. The client and the server both have a certificate from a custom CA, which I imported into firefox, along with the private key. Does someone know what the issue here might be? I am suspecting that there is some problem with firefox loading the user certificate on the preflight request?

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