Error code

Firefox SSL_ERROR_RX_RECORD_TOO_LONG

FIREFOXSSL_ERROR_RX_RECORD_TOO_LONG
Browser Error Code· An error code shown in a web browser when a page fails to load.

What it means

The TLS record Firefox received was larger than the protocol allows.

How to fix it

  1. Verify the URL uses https:// and that the server's port 443 is actually serving HTTPS.
  2. Check for a misconfigured server or reverse proxy sending HTTP when Firefox expects TLS.

Not affiliated with Firefox. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.