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How to resolve SEC_ERROR_UNKNOWN_ISSUER warning in Firefox

How to resolve SEC_ERROR_UNKNOWN_ISSUER warning in Firefox

How to resolve SEC_ERROR_UNKNOWN_ISSUER warning in Firefox – The warning error showing “Your Connection is not secure, SEC_ERROR_UNKNOWN_ISSUER” relates to the problem in our Mozilla Firefox Web Browser. Whenever we update Firefox to upgraded version 58, then this problem occurs. After that our browser do not open several sites including, or and others. In this article, we will deal with this following two methods.

Procedure to Fix SEC_ERROR_UNKNOWN_ISSUER warning in Firefox browser.

  1. Disable SSL Security Mechanism in Antivirus

We suggest you to disable the SSL Scanning in your antivirus like Avast, Bit-defender, ESET and Kaspersky. Let us take Kaspersky antivirus as a suitable example. Open Kaspersky software and click on Settings. Navigate to Additional option followed by Network. On Network Setting page, under Encrypted connections scanning section, select Do not scan encrypted connections. After setting up, your computer is left unsecure by reducing protection as modules like Parental control, URL advisor, Private browsing, web antivirus will not be able to control encrypted traffics.

In Avast Program, we can also disable SSL security mechanism by following steps given below. Open the Dashboard and go to Settings. Then go to Protection and click Customize next to web shield. There you have to uncheck the Enable HTTPS scanning setting.

In Bitdefender user required to click on Modules followed by web protection followed by Toggle off the scan SSL setting. Same with other antivirus platforms.

How to resolve SEC_ERROR_UNKNOWN_ISSUER warning in Firefox

  1. Add an Exception if website permits you –

For this setting, we have an error or warning page, just click on Advanced. Then click on Add Exception. Now a dialog box naming “Add Security Exception” will open. Next click on Get certificate and then on View if you want to refer to the certificate. Then click on Confirm Security Exception. After all Restart the Firefox browser and check if problem is solved or not.

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