If someone encounters the same thing, the solution to the two issues was:
- For the first error, it is due to a wrong deletion action. Better to use the built-in BO Operations from the UI designer actually! Thanks Horst Schaude!
- For the second error, it was due to the Alternative Key I did set up for my Custom BO.
So I suppressed the Alternative key and I modified my code in order to make sure no two Custom BO could have the same ID.
Now everything is fine!
Thank you all for your attention.
Best regards.
Jacques-Antoine