Enter a production lot number

What causes this issue?

The production lot number has not been entered.

System Response

If a production lot number has not been entered, the system tries to
determine the number using the user exit EXIT_SAPLMD07_001. The
backflushed value is however empty which causes the system to terminate
the processing.

How to fix this error?

If a production lot number has been entered, create a project for the
SAP extension MD070001 and enter the corresponding coding to enable the
production lot number to be created.

Error message extract from SAP system. Copyright SAP SE.