Hi Experts,
We have a requirement to restrict the manual entry if users enter the invalid entry in OVS field.
Custom Implementation-Embedded a custom EC in Visit quick create screen and added the custom OVS on the EC.
Problem:
1st Issue - Now the problem is, When we enter any invalid entry in OVS field (Product Group), First click of save button getting the error (From SAP Standard) but as soon as clicked on save button on second time, System allowed to save the Visit.
2nd Issue - Also, user entered value not getting the in SDK (Script) to raise the specific custom error message.
Expectation - Either with the SAP error message, save should be stopped or to suppress Standard error message and raise our own custom message.
Kindly provide your expert opinion.

Note - We raised an incident for the same, but SAP replied us, Question is out of support scope.