SAP Note No. 453577 —— Debugging in user exit EXIT

Symptom
You would like to debug the user exit EXIT_SAPLMBMB_001 of enhancement MB_CF001. In spite of an update debugging this is not possible.

Additional key words
MB_POST_DOCUMENT, update task, V1 update, update, customer function exit with update of material document.

Cause and prerequisites
This problem is caused by a program error.

The symptom first occurs after the implementation of Note 354212.

Function module MB_UPDATE_TASKS, which is an update module and is therefore called in the update task, in turn calls a function module (MB_POST_DOCUMENT) in the update task. This is not required and, under circumstances, results in debugging in function module MB_POST_DOCUMENT - and in particular in user exits located in the function module  being difficult or impossible.

In addition, the internal call of function module MB_POST_DOCUMENT in the update task is an unnecessary performance load.

Solution
Refer to the correction instruction.