Не удаётся сохранить ни одно поле в профиле

[Canapin (Coin-coin le Canapin)]

Здесь была похожая проблема (с решением). Возможно, это даст некоторые подсказки.

No user preferences updating on my site

Users are unable to change their about section in my forum. When they press save it says saved, but refreshing just clears this. Unable to reproduce on Meta. Able to reproduce when I change my bio or change someone else’s. I checked error logs, nothing showing up regarding this. Is there any place where I can begin debugging something like this? I don’t know how long this has been here only after a user reported it today.