Visitors: check the address doesn't include a port number, disable proxy/VPN and check Firefox's network settings. Site owners: make sure port 443 has SSL enabled with a valid certificate (e.g. Apache SSLEngine on in the 443 VirtualHost, Nginx listen 443 ssl).

What SSL_ERROR_RX_RECORD_TOO_LONG actually means

During a TLS handshake, Firefox reads the first record from the server. If the server isn’t speaking TLS on that port, the data looks like an impossibly long record, giving SSL_ERROR_RX_RECORD_TOO_LONG. Chrome reports the same situation as ERR_SSL_PROTOCOL_ERROR.

How it shows up

  • “Secure Connection Failed. Error code: SSL_ERROR_RX_RECORD_TOO_LONG”.
  • Only one site affected.

Common causes

  • Server not configured for HTTPS on port 443.
  • Proxy intercepting HTTPS incorrectly.
  • Wrong port in the URL.

How to fix it, step by step

  1. Check the URLRemove any port number like :80 from https:// addresses.
  2. Disable proxies and VPNFirefox Settings → Network Settings → No proxy; disconnect VPN.
  3. Test another browser/networkIf it fails everywhere, the site is misconfigured. Tell the owner.
  4. Site owners: enable TLS on 443Configure the HTTPS virtual host/server block with a certificate, then restart the web server. Check with openssl s_client -connect example.com:443.
Check it's fixed: The site loads over HTTPS with a padlock in Firefox.

Keeping it from coming back

Site owners: automate certificate renewal and test HTTPS after server changes.