Mozilla TLS Error

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  • Answered
Noob here, so I hope this is an easy fix. I recently added SSL/TLS certificate to my Wordpress Site using Really Simple SSL plug-in. The site is now loading with fine with HTTPS on Chrome, Edge, and Brave browsers. But on Firefox (mobile and desktop), I'm getting the following error: MOZILLA_PKIX_ERROR_REQUIRED_TLS_FEATURE_MISSING. The only information I can dredge up is that the OCSP Stapling (and no, I don't know what that is) is having issues and the problem is likely on the hosting side rather than the certificate. Any advice on what needs to be done so the site loads on Firefox as well?

Arnel C
  • Answered


Sorry for the error! 

FYI - OCSP is used to check the revocation status of X509 certificates.
OCSP provides revocation status on certificates in real time and is
useful in time-sensitive situations such as bank transactions and stock

Before you approach tech support make sure to check your OCSP settings in Firefox.  You can do this by doing the following:

  1. Open a new tab in Firefox, then type or paste about:config in the address bar and press the enter key.
  2. Click the button to Proceed with Caution.
  3. In the search box above the list, type ocsp. This will bring up a list of the OCSP settings.
  4. Double-click the security.ssl.enable_ocsp_must_staple preference to switch the value from true to false
  5. Then try the site again, bypassing the cache (e.g., Ctrl+Shift+r when you reload). Any difference?

I referenced this answer from Mozilla. Click on the link for other replies regarding the issue.  Disabling the "must_staple" option fixed the issue for the original question poster.

If you're still having the problem after making these changes, then please submit a technical support ticket with details on the issue to your host's live technical support team.

If you have any further questions or comments, please let us know.

Kindest Regards,

Arnel C.