Problem displaying https websites (sec_error_unknown_issuer)
Lately I have upgradet from Windows 8.1 to 10. First it seemed all right. But when I opened Firefox and wanted to open Google.com I got the error sec_error_unknown_issuer. First I cleared my cache. But It didn't work after that. So I deinstalled Firefox and installed it again. The error message is still there.
Chosen solution
Sorry for the hassle. Many users are updating their security software or enabling parental controls during or shortly after their Windows 10 upgrade, and Firefox may need to be set up to work with those changes.
Do you use Avast, BitDefender, ESET or Kaspersky security software?
If not, could you try disabling Microsoft Family Safety: http://windows.microsoft.com/en-us/windows-10/turn-off-microsoft-family-settings
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Chosen Solution
Sorry for the hassle. Many users are updating their security software or enabling parental controls during or shortly after their Windows 10 upgrade, and Firefox may need to be set up to work with those changes.
Do you use Avast, BitDefender, ESET or Kaspersky security software?
If not, could you try disabling Microsoft Family Safety: http://windows.microsoft.com/en-us/windows-10/turn-off-microsoft-family-settings
jscher2000 you're a genius !!!
I don't use Avast, BitDefender, ESET or Kaspersky security software. So I tried with the family safety. After logging in to my account I noticed I was added to a family. After I removed myself from it I tried to open google again. Now it works without any problems.
Thanks for the quick response.
I can't claim credit. This is about the fifth day of Windows 10 users having the same problem, so by now we have a good idea of what to check.