There is a deleted HU &1 in the database

What causes this issue?

You have tried to create a handling unit with an identification that
has already been assigned earlier.

How to fix this error?

Check if the data record of the deleted handling units can be archived.


&HINTS&
Only those handling units with the status planned are deleted. All the
other handling units will not be deleted from the database due to
history reasons.

Error message extract from SAP system. Copyright SAP SE.