Getting HTTP 431 - Request Header Fields Too Large. How to Fix This Error? or HTTP 431 Error: Why Are

Ran into this too! For me, it was a combo of auth tokens + random tracking cookies.

Try this:
1. Clear ALL cookies (not just some).
2. Use incognito mode to test—sometimes extensions add junk headers.

If it’s still happening, your backend might need tweaking. Some servers (like Nginx) let you adjust the `large_client_header_buffers` setting.