I discovered this on the Rust Users forum and was told this was probably your bug. Sure enough, it’s also reproducible here on meta.discourse, so I’ve copy pasted it from my original post on Rust-Users:
In the settings for my original account on this forum, I set my interface language to Esperanto. Ever since, the website is blank when I’m logged in to that account – the title bar loads, and view source shows a bit of html with some javascript, but the page appears entirely white. I have tried it in: Firefox Nightly on Linux, Firefox 56.0 on Linux, Firefox Nightly on Android. The only way I can get back to this forum is by deleting cookies to log out from that account. I hadn’t used the account for anything yet, so it’s no real loss if I can never get back in to it, but I don’t think Esperanto should be a language option if choosing it means banishment .
I see there are some other bug reports here with the same observable behavior, but those are all fixed, so I guess this has a different cause.