SSL_ERROR_NO_CYPHER_OVERLAP Browser Origin: On your device Last updated 15 Oct 2026

Firefox: Secure Connection Failed — SSL_ERROR_NO_CYPHER_OVERLAP (no common cipher)

Firefox and the server share no TLS cipher suite, so the secure handshake cannot even start.

Exact message you may see Secure Connection FailedAn error occurred during a connection to
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Seen on: Firefox Nginx Apache

Meaning

Common with very old servers (weak ciphers only), or hardened servers that allow a tiny cipher list Firefox does not support, and with server software that disabled all modern suites by mistake. Fix the server's ssl_ciphers/SSLCipherSuite and protocols.

Common causes

  • Server offers only obsolete ciphers (RC4, 3DES, export grade)
  • Cipher list too restrictive or misspelled
  • TLS 1.2/1.3 disabled on the server
  • Load balancer/appliance with outdated firmware
  • Certificate type (e.g. ECDSA only) not supported by a legacy client

⚡ Quick fix

  1. Owners: enable TLS 1.2/1.3 and a modern cipher list
  2. Use the Mozilla SSL configuration generator for your server
  3. Update the load balancer/appliance firmware

Detailed fix by platform

Nginx

  1. ssl_protocols TLSv1.2 TLSv1.3; ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384;

Apache

  1. SSLProtocol -all +TLSv1.2 +TLSv1.3 and SSLCipherSuite ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256

Linux

  1. nmap --script ssl-enum-ciphers -p 443 example.com lists what the server offers

How to diagnose

  1. Ciphers — What does nmap show?
  2. Protocols — TLS 1.2+ enabled?
  3. Config — Recent hardening changes?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: On your device. Errors that are often confused with or caused by this one (click to open):

A TLS error caused the secure connection to fail — Safari: Safari Can’t Open the Page — A TLS error caused the secure connection to fail (Browser)A TLS error caused th…ERR_CONNECTION_CLOSED — Chrome: This site can’t be reached — example.com unexpectedly closed the connection. ERR_CONNECTION_CLOSED (Browser)ERR_CONNECTION_CLOSEDERR_SSL_OBSOLETE_VERSION — Chrome: Connection not secure — ERR_SSL_OBSOLETE_VERSION (old TLS 1.0/1.1) (Browser)ERR_SSL_OBSOLETE_VERS…ERR_SSL_PROTOCOL_ERROR — ERR_SSL_PROTOCOL_ERROR (This site can't provide a secure connection) (JavaScript)ERR_SSL_PROTOCOL_ERRORERR_SSL_VERSION_OR_CIPHER_MISMATCH — Chrome: This site can’t provide a secure connection — uses an unsupported protocol. ERR_SSL_VERSION_OR_CIPHER_MISMATCH (Browser)ERR_SSL_VERSION_OR_CI…HSTS — Chrome: You cannot visit example.com right now because the website uses HSTS (NET::ERR_CERT_… no bypass) (Browser)HSTSNET::ERR_CERT_REVOKED — Chrome: Your connection is not private — NET::ERR_CERT_REVOKED (the certificate was revoked) (Browser)NET::ERR_CERT_REVOKEDSEC_ERROR_UNKNOWN_ISSUER — Firefox: Warning: Potential Security Risk Ahead — SEC_ERROR_UNKNOWN_ISSUER (certificate not trusted) (Browser)SEC_ERROR_UNKNOWN_ISS…SSL_ERROR…

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