The contract has to end on or before the validity time (&1 &2)

What causes this issue?

You have entered a contract end that lies before the change date entered
on the initial screen. The change date is not allowed to be outside of
the validity period of the contract.

System Response

The system sets the contract end to the change date.

How to fix this error?

If you want to enter an earlier contract end than the change date, go
back to the initial screen and adjust the change date.

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.