Your connection is not secure

Hi guys, my granddaughter has this popping up everywhere she try's to go outside of Firefox ! It will open FF and IE fine but if she try's to go to any other site this message pops up !! We were trying to open Google, like i said every site gives this message. We checked the clock & date, they are correct !! Now i am lost, any ideas of what to try would be appreciated very much ! She doesn't use her computer much so it may be awhile before i get back with an answer for you !!
Thanks

Your connection is not secure

The owner of Google 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 only connect to it securely. As a result, it is not possible to add an exception for this certificate.


Forgot to mention that everything works fine in "Safe Mode with networking"

Hi, just a quick comment as I've not seen this and a quick search on this site indicates this error message has not been reported here before, but it is reported on the internet.

If you search for either of the two larger paragraphs of the message generally, you will find discussions on it which may help you. As I've not encountered this, maybe someone else will come along and help you.


Tech-ish discussion here:
firefox - Facebook.com returning invalid security certificate - Super User

I've looked at some of the search results and there's not immediately a clear answer.

This older post suggests a link with the user's AV - which are you using?
certificate error in Firefox in Yahoo and Google. - Kaspersky Lab Forum

Hi, some have found that their browser is set up to use a proxy. For example, Kaspersky when configured to scan SSL.
(Ok, you use AVG).

I would check your browser's proxy settings and make sure it is set to
"auto detect proxy settings for this network"

Note that in Safe Mode with Nwkg of course your AV is not running.

That gives a big clue: so another diagnostic route you can take is from a clean boot:
Clean Boot - Perform in Windows 10 to Troubleshoot Software Conflicts - Windows 10 Forums

Hi- try the clean boot approach above- adding this post so you're notified..

I would fix the problem first.. if you're unlucky you'll have more problems if you upgrade to '10. And before you upgrade to '10 make sure you have a current disk image and a boot disk for the imaging program ready.

When you do upgrade, make sure you'll have Win 10 drivers available - the laptop is compatible- and download and create bootable install medium rather than using the download. That way it's ready to
a. upgrade other PCs
b. ready for a 2nd attempt if needed
c. available should you wish to do a in-place upgrade repair install (great repair technique).