Mozilla Firefox Errors: Unable to Connect, Server not found and other issues

I’ve had several of my clients run into this Mozilla Firefox security issue recently and it has not been an easy one to resolve. However, with some research and trying a combination of things, I have resolved this for them now. Here’s how I did it.

Here are some of the ways that these issues presented .

  • Many secure websites will not load
    • When Firefox connects to a secure website (the URL begins with “https://”), it must verify that the certificate presented by the website is valid and that the encryption is strong enough to adequately protect your privacy. If the certificate cannot be validated or if the encryption is not strong enough, Firefox will stop the connection to the website and instead show an error page stating “Your connection is not secure”.
  • The certificate is not trusted because the issuer certificate is unknown.
    • 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
  • Youtube Videos won’t play: “An error occurred. Please try again later.
  • Any HTTPS sites don’t load completely – missing images and style.
  • Uninstalling Firefox and re-installing it does not resolve the errors.
  • Uninstalling Java, mad it impossible to re-install Java on the machine.

What worked to resolve the above browser related issues.

Both clients were running Eset Nod32 anti-virus, not sure if it was a key issue that this particular anti-virus was involved, but any anti-virus could be the issue. Further, each PC had Adobe Air, Adobe Flash and Java installed.

I backed up their files just to be sure that nothing would happen to their data when I began to make changes to their computer.

I deleted their “Temp” files. Open up Windows Explorer and in the address bar type ”  %temp% ” . This will take you to the Temp folder for this machine. Click on folder, then click CTL + A to select all files and click delete. Some files may not be able to be deleted and you may be presented with a prompt to “Skip” deleting these files. That is fine – you can skip deleting those that are actively being use by the system.

Next, go to the “Control Panel” and “add/remove software”. Located Adobe Air, Adobe Flash, Mozilla Firefox and Java and uninstall them all.

This may require a restart of the machine.

Go back into “add/remove software” and uninstall your anti-virus program. Make sure before you do so that you have the license number and software to re-install it.

This may require a restart of the machine.

Once the computer has restarted, open up Internet Explorer or Google Chrome to download the latest version of Mozilla Firefox. Here’s a link to download Firefox for you.

Test to see if you can load Google’s home page https://www.google.com or visit Youtube https://www.youtube.com and play a video without issue. If you can, then you have resolved your issue.

Don’t visit many websites until you re-install your anti-virus. If you can visit Google’s home page (which is HTTPS) and play videos on Youtube, then you have most likely resolved your issue.

Next, re-install the other applications that you uninstalled from your system like Adobe Flash, Adobe Air, and the latest version of Java if you need to.

Test your browser again.

If everything is still working, you now re-install your anti-virus software.

Hope this works for you as well as it did for me.