The mandate &1 is obsolete

What causes this issue?

The mandate has been inactive for longer than 36 months (since the date
of the last usage) and cannot be used as it is no longer valid.

System Response

You cannot save your entries.

How to fix this error?

Try again, but specify another mandate that is in the validity period.

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.