&1: &2 (T4)

What causes this issue?

The finish date of the order proposal lies in the past.

System Response

This exception is displayed in the MRP list and in the
stock/requirements list.
This situation may occur if in Customizing for the plant in question,
the automatic forward scheduling was switched off for MRP.

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

How to fix this error?

Check whether the order proposal should be rescheduled.

Error message extract from SAP system. Copyright SAP SE.