hi Ariaoth, we have seen other users report this problem in two circumstances recently: either if they had an old version of kaspersky security software running on their device or on accounts with usernames containing non-latin characters. would one of these cases apply to you too?

Which account ? I couldn't understand that. By the way, I'm not using old version Kaspersky.

that would be your windows user name...

It have "ı". Maybe it's non-latin but it's my name and surname enrolled in outlook, so I can't change it.

ok, thanks for confirming - our developers are currently looking into the matter in https://bugzilla.mozilla.org/show_bug.cgi?id=1418325 in case you want to follow along there...

hi again, i think we have fixed this issue now with the updated firefox 57.0.1 which is available through https://www.mozilla.org/en-US/firefox/all/