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Suddenly all web site secerity certificates are invalid, I've followed the help page recommendations to no avail, and reloaded firefox. That didn't work either

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I started getting the following message on all of my open tabs in Firefox: Your connection is not secure

The owner of www.yahoo.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.

This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox may only connect to it securely. As a result, it is not possible to add an exception for this certificate.

Learn more…

Report errors like this to help Mozilla identify and block malicious sites

www.yahoo.com uses an invalid security certificate.

The certificate is not trusted because the issuer certificate is unknown. The server might not be sending the appropriate intermediate certificates. An additional root certificate may need to be imported.

Error code: SEC_ERROR_UNKNOWN_ISSUER

I went to the help page in Firefox and got the same message. So I went to the Firefox help page in a different browser and read and followed the article for this problem. All of those sites work in other browsers. The only AV I currently have installed is MS Defender. And reloading Firefox hasn't helped. Disabling all add-ons hasn't helped. Rebooting the computer hasn't helped. What is left other than resetting the computer and starting over?

I started getting the following message on all of my open tabs in Firefox: Your connection is not secure The owner of www.yahoo.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website. This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox may only connect to it securely. As a result, it is not possible to add an exception for this certificate. Learn more… Report errors like this to help Mozilla identify and block malicious sites www.yahoo.com uses an invalid security certificate. The certificate is not trusted because the issuer certificate is unknown. The server might not be sending the appropriate intermediate certificates. An additional root certificate may need to be imported. Error code: SEC_ERROR_UNKNOWN_ISSUER I went to the help page in Firefox and got the same message. So I went to the Firefox help page in a different browser and read and followed the article for this problem. All of those sites work in other browsers. The only AV I currently have installed is MS Defender. And reloading Firefox hasn't helped. Disabling all add-ons hasn't helped. Rebooting the computer hasn't helped. What is left other than resetting the computer and starting over?

Chosen solution

Kamrul Hassan said

  • Try re-installing your firefox, first of all remove it from you computer by going to Program and Features: Control Panel\Programs\Programs and Features
  • Then remove the firefox and later check at the /c drive if there is any firefox folder if there is then delete it and even check in the desktop if there is any folder.
Then visit this site: https://www.mozilla.org/en-US/firefox/desktop/ And download and re-install firefox later it might ask you to restore your setting don't do that, simply there will be a message saying that to delete all your settings, browser history and files to be deleted and start freshly, do it. See if still your problem exists or not. If it still exists then try to do the above (*) marked steps and download the beta version and install it: https://www.mozilla.org/en-US/firefox/channel/desktop/#beta
  • Note that Yahoo and other mail sites don't get full rights to use as firefox blocks it for security purpose. I would like you to use a better and best antivirus like Kaspersky and Norton. Which are advanced in technology and up to date security. Much suitable for latest web browsers.
Hope to hear from you about your problem.

Well iemnuke65 said

I finally got it to work. I tryed your methodology but still had the problem. Eventually I uninstalled the last Windows update and reinstalled it. And now everything is working. I just wonder how long it will last.

Well the windows update doesn't have interfered with your firefox browser, as I am using so it didn't gave me any problem till now. Well if your windows updates is uncorrected some how it may cause errors. So, always try to update your PC to the up-to-date version and make sure all updates are completed.

I hope your problem as you mentioned so this topic can be marked as solved if you want.

Read this answer in context 👍 0

All Replies (4)

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  • Try re-installing your firefox, first of all remove it from you computer by going to Program and Features: Control Panel\Programs\Programs and Features
  • Then remove the firefox and later check at the /c drive if there is any firefox folder if there is then delete it and even check in the desktop if there is any folder.

Then visit this site: https://www.mozilla.org/en-US/firefox/desktop/ And download and re-install firefox later it might ask you to restore your setting don't do that, simply there will be a message saying that to delete all your settings, browser history and files to be deleted and start freshly, do it.

See if still your problem exists or not. If it still exists then try to do the above (*) marked steps and download the beta version and install it: https://www.mozilla.org/en-US/firefox/channel/desktop/#beta

  • Note that Yahoo and other mail sites don't get full rights to use as firefox blocks it for security purpose. I would like you to use a better and best antivirus like Kaspersky and Norton. Which are advanced in technology and up to date security. Much suitable for latest web browsers.

Hope to hear from you about your problem.

Modified by user1402432

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I finally got it to work. I tryed your methodology but still had the problem. Eventually I uninstalled the last Windows update and reinstalled it. And now everything is working. I just wonder how long it will last.

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Note that you can click the blue SEC_ERROR_UNKNOWN_ISSUER error message to expand this section and show the certificate chain.

You can use an online decoder to decode the certificate and inspect the issuer.

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Chosen Solution

Kamrul Hassan said

  • Try re-installing your firefox, first of all remove it from you computer by going to Program and Features: Control Panel\Programs\Programs and Features
  • Then remove the firefox and later check at the /c drive if there is any firefox folder if there is then delete it and even check in the desktop if there is any folder.
Then visit this site: https://www.mozilla.org/en-US/firefox/desktop/ And download and re-install firefox later it might ask you to restore your setting don't do that, simply there will be a message saying that to delete all your settings, browser history and files to be deleted and start freshly, do it. See if still your problem exists or not. If it still exists then try to do the above (*) marked steps and download the beta version and install it: https://www.mozilla.org/en-US/firefox/channel/desktop/#beta
  • Note that Yahoo and other mail sites don't get full rights to use as firefox blocks it for security purpose. I would like you to use a better and best antivirus like Kaspersky and Norton. Which are advanced in technology and up to date security. Much suitable for latest web browsers.
Hope to hear from you about your problem.

Well iemnuke65 said

I finally got it to work. I tryed your methodology but still had the problem. Eventually I uninstalled the last Windows update and reinstalled it. And now everything is working. I just wonder how long it will last.

Well the windows update doesn't have interfered with your firefox browser, as I am using so it didn't gave me any problem till now. Well if your windows updates is uncorrected some how it may cause errors. So, always try to update your PC to the up-to-date version and make sure all updates are completed.

I hope your problem as you mentioned so this topic can be marked as solved if you want.