After updating my Firefox, I could not open several sites, including Google.com, Twitter.com, Facebook.com, etc. I received the error – Your Connection is not ...

A lot of users are reporting that when they try to access a website or a local web server, they see SEC ERROR REUSED ISSUER AND SERIAL warning. This issue is usually ...

I'm trying to access the website of a portuguese delivery company to track an order (https://tracking.dpd.pt/track-and-trace), but I'm getting an unknown certificate ...