Invalid value for minimum retention period

What causes this issue?

A non-permissible value was entered for the maximum retention period.
You can enter specific values (positive whole numbers) or the value -1
for ?irrelevant?.

System Response

Your input is rejected.

How to fix this error?

Enter a valid value.

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.