hi Skullx, sorry for a late reply. there are a couple of similar other user reports, so we are looking into the issue in https://bugzilla.mozilla.org/show_bug.cgi?id=1528317. are you able to trigger the error message somewhat reliably with particular steps? if so, could you please capture a http log while the problem is occurring which would help mozilla's developers understand what's going on and how to fix it: https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/HTTP_logging#Using_aboutnetworking (it would probably best if you upload the log via https://send.firefox.com/ and send me a [https://support.mozilla.org/en-US/messages/new?to=philipp private message] here on the support site with the link you've received there )