All Browsers on linuxmint give SSL certificate error for firefox.com

[brain8891]

I tried to login, into firefox to sync it, but I was faced with this erorr:

"
Secure Connection Failed

An error occurred during a connection to accounts.firefox.com. The server uses key pinning (HPKP) but no trusted certificate chain could be constructed that matches the pinset. Key pinning violations cannot be overridden. Error code: MOZILLA_PKIX_ERROR_KEY_PINNING_FAILURE

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.
"

1- tried access Accounts.firefox.com on chrome, it gave me the same error. Hence, I used Google Chrome and Firefox(mint) but both gave me the certificate error.
2- I started with a new Firefox profile, it did not help.
3- the time/Date is correct.
4- ran a [ping Accounts.firefox.com ] waited for a minute and nothing happened.
5- other websites work.
6- I assume it is a system wide issue, so does that mean I have to reset a certificate cache?
7- Windows on a different machine can access firefox.com

Thank you.

And do you guys prefer to install the vanila version of firefox, and does it update automatically? since it is not in the software manager?
I am new to LinuxMint
Thank you, again!

[Pjotr]

"All browsers": exactly which ones did you try?

[brain8891]

Google Chrome and Firefox(mint)