I asked a question on askubuntu.com. (https://askubuntu.com/questions/1111486/upgrade-from-16-04-to-18-04-broke-apt)  
First it was put on hold, because it was too broad. So I edited my question to make it more specific.  
Some hours later the question was deleted without any comment.  

 - I researched half a day before asking the question.
 - The English was not the best, but it was ok.
 - As far as I perceived it the question was detailed and very specific.

So I can't think of any reason why my question was deleted.  
I'd be glad if anyone could help me solving this mystery.