Well Ed_S what can I say besides
THANK YOU SO MUCH
In fact your little hint did the trick. I just wrote one new message and posted another answer and then the error disappeared.
Even being my hero for the moment does not free you from further questions I hope you are OK with giving me some more understanding of what in hell happened here.
First of all to give me a better understanding of how to read the logs. I mean, what a great guess you made. What did you lead to think about a serialization problem might be the one breaking it?
Why not the
cook_url or I do not know, anything else?
Secondly what are your consumptions, do I have to be aware of running in such a problem again? Or maybe with another user?
Do you think there is a way to narrow it down which message, user, image could be the bad guy here. Is there any other chance to take a look into that than … clicking through the messages and hoping to get a effect on one of the private messages posts?
The funny thing is that some admins just did the exact same thing, like writing a new message (topic) to the affected account and we did experience any other behavior. Somehow the last sent message from me to the affected account did the trick.
And the last one, can I have your phone number for further emergency shout outs? Just kidding!
But for real, thanks a lot, a lot lot, a lot lot lot. I really got stuck here an I am so glad that our user – as I mentioned, one of our admins – can get back on track. Thank you Ed_S!