I tried to create a sample application where I can trigger this error, but I did nog succeed in that...
In the image you'll see the error. Also note that the text that was edited by the user, changed to some weird text. In the field Oproepnr. on the top-left the user entered “RAMING_K691” but the text changed after saving the data.

Are you familiar with this kind of problem?
I'm using the latest version of the mysql-components on Delphi 7.
The MySQL-server version is 5.6.25.
Thanks
Wim