Hi dave.kydd, I assume non-secure connections are okay? For example: http://www.example.com/ The PR at the beginning of PR_END_OF_FILE_ERROR usually refers to a proxy or "man in the middle" of your browsing connections. That might be a security software filter or something else. Sometimes it is a problem with a VPN. Does anything in the support article help with tracking it down: [[Secure connection failed and Firefox did not connect]].