Not sure what fixes it to be honest. Over time I've added various different dynamic pages based on different tables etc using DataBridge. It seems OK most of the time, but sometimes seem to get this happening and never sure why, as I don't change any settings. And invariably it starts working again at some point.
I found this old thread that sounded similar:
I think you're probably right about the host settings though. Had no joy with the Remove Connection Scripts thing. I've been trying to define a new DB connection in DataBridge, and am getting an error about there either being no testing server, or the testing server not mapping correctly.
Mentions a file ../_mmServerScripts/MMHTTPDB.php.
Had a look in the file manager on the control panel, and that folder is empty on the domain that doesn't work, and the one that does work contains that file and a few others like mysql.php and WA_DBScript.php that sound important.
Not sure if they would have been deleted doing the Remove Connection Scripts thing, or if that was just something local?
I've found the _mmDBScripts folder in the Configuration folder, and reuploaded the three in there:
to the _mmServerScripts folder.
Checked the permissions were the same as the other domain, tried again, still no joy.