Hello, please check you system Date and time and make sure they are correct . Moreover A common problem recently is Firefox not being set up to work with your security software. Some security suites include a filtering feature. In order to filter secure connections (HTTPS URLs), the security software presents a fake certificate to Firefox so it can intercept and stand in the middle of the secure connection. To have Firefox trust these certificates, you may need to do something such as import a root certificate, or click something in your security software's settings.