Expiration date & of batch does not match entered expiration date &

What causes this issue?

A <DS:GLOS.shelf_life_expiration_date>shelf life expiration date</> has
already been defined for this <DS:GLOS.batch>batch</>.
However, the expiration date that you entered is different from that of
the batch.

System Response

Depending on how the System is configured, this message is either a
warning or an error message.

How to fix this error?

Check the expiration date or the batch number.
If this message is an error message, you can
either terminate the current transaction
or enter a new batch
If the message is a warning, you can post the goods receipt.
The old expiration date of the batch is retained.

Error message extract from SAP system. Copyright SAP SE.