No unit entered

What causes this issue?

No unit has been specified for the retention period although a specific
value exists for the minimum or maximum retention period.

System Response

The entry is rejected.

How to fix this error?

Specify a unit for the retention period or change the value for the
minimum or maximum retention period to -1 (irrelevant).

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.