Dear marcbote,
The activation of the piped logs did not fix the problems (I have over 1300 domains on this particular server).
So I did the nickpick-solution.
That helped and I got the sites up again.
I also tested the igorx-solution. That worked too.
I read that nickpick switched to Ensim...
That is not an option for me, because Ensim does not (yet) have a migration utility.
The activation of the piped logs did not fix the problems (I have over 1300 domains on this particular server).
So I did the nickpick-solution.
That helped and I got the sites up again.
I also tested the igorx-solution. That worked too.
I read that nickpick switched to Ensim...
That is not an option for me, because Ensim does not (yet) have a migration utility.