Hi,
I have also the same problem; I am trying to cancel the saving process of the ETM document by raising an error message in USEREXIT_SAVE_DOCUMENT_PREPARE(MJ3GFFZZ).
The error was successfully displayed. However, when you press enter the document is saved.
I tried the solution here but it does not solve my problem. Hope you can help me.
USEREXIT_SAVE_DOCUMENT_PREPARE in MJ3GFFZZ
TIA,
Paul More