Hi,
I like those "Mark as read" buttons in forums. Unfotunately, I cannot use it here for ALL forums (the global button on the start page of the forum). I get the following error:
Does anyone know about it?

It does it to me too, but when it give you that error it gives you a link to see all of your unread posts. If you click that link and then click "Mark As Read" it pretty much does what you are looking for.

_________________
If all else fails, use a bigger hammer.

Okay, but I found only a Link for unread posts separately for each section. So I have to do that three times to mark all posts. but - it works, thank you

Attached is a series of Screenshots with the process I took. I only had to do it once for the whole forum.

_________________
If all else fails, use a bigger hammer.