Issue in background processing- Very Urgent

Question

A custom program which is  scheduled to run every day as a background job, Failed yesterday with the below system log:
R3JD: SQL UPDATE FAILED. Error in ZMOMPO05. Contact R3JD Support. R3JD
Additional Info: A2000_UPDATE_PROCESS UPDATE ZMPOR FAILED.           
Additional Info: SY-SUBRC RETURN CODE: 4                             
Transaction termination ZZ 999 ( ZMOMPO05 )
It got failed while trying to update a custom table, but when we tried to run manually in the foreground it got completed successfully, and also the problem was only for that day, as it was doing well before it failed yesterday and even today it has completed successfully as a background job itself .
I am doing an RCA on this, any sought of help would be appreciated.
Thank you

Answer 1

Hi,
Lets take a look at the help for the UPDATE command:
SY-SUBRC = 4 - At least one line was not able to be changed, either because no appropriate line was found, or because the change would generate a line that leads to double entries in the primary key or a unique secondary index in the database table.
To keep it simple I will assume the Z table does not have a unique secondary index. It is most likely that the update failed because the program tried to update a record that did not exist in the Z table. The best you can do is add reporting to the Z program so should the problem occur again you will know exactly why. You can do this by adding a SELECT statement that tries to read the record you are about to update and report an error if the record does not exist. To improve performance you could execute the SELECT after the UPDATE fails just to prove it is missing data.
Alternatively you could replace the UPDATE with a MODIFY statement so the record will be created if it does not already exist.