How to fix an 'SSL_ERROR_NO_CYPHER_OVERLAP' error?

Common Error Codes
Reudiger Dalchow
Published: 2 March 2023Last updated: 28 April 2024
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As the message implies, this particular error relates to an issue with the secure connection between a web browser and website. Specifically, that the relevant secure connection cannot be completed for some reason, preventing the webpage from loading.

Here’s what you need to check.

Advice for website owners and operators

In most cases this problem is due to a problem between the user’s Firefox browser and your webhost. But there is one server configuration you need to check – whether your website is using an older security technology. It could be that your website is using an outdated encryption technology that is no longer supported by Firefox because it has been superseded.

The fastest way to see whether your website is using an outdated cipher suite like RC4 is to manually enable outdated SSL and TLS certificates in Firefox. You can do this by:

  • Open your Firefox settings by typing about:config into the address bar and pressing Enter
  • The browser will warn you to proceed with caution – click the Accept the risk and continue button
  • Under the Advanced Preferences menu, find the security.ssl3.dhe_rsa_aes_128_sha setting and set to True. Do the same for the security.ssl3.dhe_rsa_aes_256_sha and security.tls.version.enable-deprecated settings
  • Try loading your website again

If you find you can access your website after making these changes, you will definitely need to update your SSL/TLS cipher suite. The fastest and most effective way to do this is by enabling the free wildcard SSL certificate included with your webhosting package – see our instructions on how to activate your free SSL certificate.

There is one other reported cause of the SSL_ERROR_NO_CYPHER_OVERLAP – the Cloudflare distribution network. Apparently some Firefox users run into problems because their web browser does not support Cloudflare’s Server Name Indication (SNI) protocol. To avoid similar issues for your users, consider switching to the free 20i CDN for your web acceleration needs.

What else do I need to know?

The SSL_ERROR_NO_CIPHER_OVERLAP error is only found in the Firefox web browser.