I usually mark a bunch of threads I no longer post on as read in order to clear my 'new replies' page and keep it clean.
Recently, whenever I go to to it (this also happens in the 'unread posts' page) it comes up with a server verification error. Even after refreshing the tab/closing an opening it.
The same applies for logging out.
Note: I use Safari not chrome on mobile. Not sure if the same happens if you use Chrome or another mobile search app.
