I can say it appears there is a warning after editing a post but not prior to submit.
I picked one post from the error and deleted all the line feeds and white space.
Hoping it would fit
But when I submitted the edit I got the same error.
Data too long for column 'POST_BODY' at row 1

I appeared as if it came from UBB because it had the same scheme as the default style.

Blue Man Group
There is no such thing as stupid questions. Just stupid answers