This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

This thread was archived. Please ask a new question if you need help.

[Solved] certificate contains unknown critical extension error firefox 5

  • 1 reply
  • 28 have this problem
  • 4 views
  • Last reply by mtimmjcp

mtimmjcp
mtimmjcp
more options

Secure connection failed An error occurred during a connection to an internal website Certificate contains unknown critical extension (Error code: sec_error_unknown_critical_extension)

Secure connection failed An error occurred during a connection to an internal website Certificate contains unknown critical extension (Error code: sec_error_unknown_critical_extension)

Modified by the-edmeister

All Replies (1)

mtimmjcp
mtimmjcp Question owner
more options

I imported the root chain for my internal CAs into FireFox and this fixed the problem. Tools->Options->Advanced->View Certificates->Import