The forum I called wiki base was the namespace of the same name. I had some articles in it.
It was displayed in a private committee forum, so wiki base appeared as a wiki container at the top of that forum.
I wanted to create another related container and put it in a different more accessible forum. I created the child namespace Dev from Wiki Base.
When I looked at the namespace control panel, wiki base had been renamed to Dev. There was no child namespace. I am not sure how a child namespace would be displayed.
I decided to not worry about that and just change the display location of what had been Wiki Base and was now Dev to the other forum.
Now any time I read an article in the wiki base/dev forum in its new display location, the database error occurs.
It was not clear to me from the instructions that I needed to create a child forum from the top level forum of a namespace in order to create a child namespace. I presume that is what I did wrong.
You have full admin access to my site that I gave you several weeks ago if you want to look at it there.
By the way there is no attachment button or link in this editor either or I could show you the screen shots.