SEC_ERROR_UNKNOWN_ISSUER problem in Mozilla Firefox fix

Are you seeing ‘SEC_ERROR_UNKNOWN_ISSUER‘ error code in the Firefox window? If you are seeing this error, then you can’t access any website using Firefox, unless you fix this issue. The main culprit behind this problem is root certificate, which when disabled causes this trouble.


1. Close any opened instance of Mozilla Firefox on your computer. Launch Firefox again.

2. Temporarily disable the antivirus and firewall on your computer. Try to open any site from Firefox. Check if it works.

Simply follow these steps to fix the issue by enabling the particular root certificate-

Fix 1 – Enable ‘security.enterprise_roots.enabled’ in Firefox-

Follow these steps-

1. Open Mozilla Firefox on your computer.

2. In Firefox window, copy-pasteabout:config” in the address bar and hit Enter.


About Config


3. Now, you will receive a message of caution. Click on “Accept the Risk and Continue” to proceed further.


Accept And Risk And Continue


Advanced Preferences tab will be opened.

4. In the Advanced Preferences tab, click on the Search box and type “security.enterprise“.

5. In the search results, you will notice “security.enterprise_roots.enabled” and the status of it, normally stating “false“.

6. Click on the arrow sign of the particular option to switch its value to “true“.


Click On Flase


7. Click on the home icon just beside the address bar to go to the homepage on your browser.


Home True


That’s it! Try to open any website on Firefox.

Fix 2 – Refresh Firefox

1 – Open Firefox Browser

2 – Click on 3 horizontal bars styles menu

3 – Now, click on Help

Helpfirefox Min



4 – Click Troubleshoot Mode

Troubleshoot Firefox Min


5 – Now, click on Restart

Restart Mozilla Min


6 – Click on Refresh Firefox

7- Again Click on Refresh firefox finally

8 -Click Next

Your Firefox will be refreshed with a new Profile folder

Fix 3 – Disable Proxy

1 – Search change proxy settings in Taskbar search box

2 -Now, click on it

Change Proxy Settings Min


3 – Now, turn Off manual Proxy setup

Off Manual Proxy Min

Now, try using Firefox again

Fix 4 – Disable Firefox extensions

1 – Open Firefox

2 – Copy and paste the path below in Firefox address bar and Hit Enter key from keyboard


3 – Disable all extesnsions and relaunch Firefox again

Extension Disable Min

You will not face this error again. Your problem should be solved.