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

Chrome: This site can’t provide a secure connection — uses an unsupported protocol. ERR_SSL_VERSION_OR_CIPHER_MISMATCH

The browser and the server could not agree on a TLS version or cipher — the server is too old or misconfigured, or the browser is.

Exact message you may see uses an unsupported protocolThis site can’t provide a secure connection
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Seen on: Chrome Edge Nginx Apache

Meaning

Modern Chrome needs TLS 1.2 or 1.3 with strong ciphers. Old servers offering only TLS 1.0/1.1 or weak RC4/3DES ciphers cannot connect; so can servers with a broken or missing certificate for the requested host. Owners should enable TLS 1.2+ and a modern cipher suite.

Common causes

  • Server supports only TLS 1.0/1.1 or weak ciphers
  • SSL protocols disabled by a hardening change
  • Missing or default certificate for the hostname (SNI)
  • Outdated browser/OS
  • Proxy or antivirus terminating TLS badly

⚡ Quick fix

  1. Owners: enable TLS 1.2/1.3 and a modern cipher list
  2. Test the site with an SSL checker (Qualys SSL Labs)
  3. Visitors: update the browser and OS, and test without antivirus HTTPS scanning

Detailed fix by platform

Nginx

  1. ssl_protocols TLSv1.2 TLSv1.3; and ssl_ciphers HIGH:!aNULL:!MD5; then nginx -t && systemctl reload nginx

Apache

  1. SSLProtocol -all +TLSv1.2 +TLSv1.3 in the SSL vhost

Linux

  1. Probe the server: openssl s_client -connect example.com:443 -tls1_2 and nmap --script ssl-enum-ciphers -p 443 example.com

How to diagnose

  1. Versions — Which TLS versions does the server offer?
  2. Cert — Valid certificate for this exact host?
  3. Client — Old browser or OS?

🔧 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):

526 — Cloudflare Error 526: Invalid SSL Certificate (Cloudflare)526A 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…Challenge failed for domain — Let’s Encrypt / Certbot: Challenge failed for domain example.com — Invalid response from http://example.com/.well-known/acme-challenge/x: 404 (SSL / TLS)Challenge failed for …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_ERRORHSTS — Chrome: You cannot visit example.com right now because the website uses HSTS (NET::ERR_CERT_… no bypass) (Browser)HSTSNET::ERR_CERT_COMMON_NAME_INVALID — NET::ERR_CERT_COMMON_NAME_INVALID: Your connection is not private (certificate is for a different domain) (SSL / TLS)NET::ERR_CERT_COMMON_…ERR_SSL_V…

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