Fix ERR_SSL_VERSION_OR_CIPHER_MISMATCH

What it means

A secure connection needs both sides to use the same encryption rules.

• TLS version. Newer versions are stronger.
• Cipher suites. The algorithms used for encryption.

If the browser and the server share no TLS version or cipher, Chrome shows ERR_SSL_VERSION_OR_CIPHER_MISMATCH.

Common causes:

• The server uses old TLS versions or weak ciphers.
• The browser is very old.
• Cached browser data is damaged.
• Antivirus or a firewall interferes with secure connections.
• The site has no valid certificate for the domain you opened (for example, a certificate for www only).

Diagnose

1. Use Qualys SSL Labs (SSL Server Test). It shows the supported TLS versions and ciphers of a site.

   

2. Open the Security tab in the browser developer tools to see the connection details.

Fixes for visitors

1. Clear the cache and cookies.

   

2. Update your browser to the latest version.

   

3. Turn off your antivirus or HTTPS scanning for a moment and test.
4. Clear the SSL state. On Windows, open Internet Options, then the Content tab, then click Clear SSL state.

   

Fixes for site owners

1. Use TLS 1.2 and TLS 1.3, and turn off older versions. Ask your host to update the server settings if you cannot.
2. Use strong, current cipher suites. Mozilla's SSL Configuration Generator gives you a safe list.
3. Make sure the certificate covers all names you use, with and without www.
4. Install the full certificate chain.
5. After the change, reload the web server and test again.

Prevent it

• Keep your browser updated, so it supports current TLS.
• Check that sites use HTTPS and show a padlock.
• Keep the SSL/TLS settings of your server up to date.

Quick recap

• The browser and server share no TLS version or cipher.
• Visitors: clear cache, update the browser, check the antivirus.
• Owners: enable TLS 1.2/1.3, use modern ciphers, and cover all domain names.