The & batch will be automatically set to &

What causes this issue?

You have not specified the receiving or issuing batch. Therefore, the
system automatically set the number of the issuing or receiving batch or
automatically determined a batch number.

System Response

Depending on the system configuration, this message is either a
completion message or a warning message. If the system is configured to
issue an error message, it automatically determines a batch number if
internal batch number assignment has been activated and is allowed for
this particular movement type.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
You set internal batch number assignment for goods receipts in
Customizing for <LS>Batch Management</> via <LS>Define New Creation of
Batch -> Define New creation for Goods Movements</>.
ENDIF.

How to fix this error?

The batch that is set automatically can only be changed if the system
issues a warning message.

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.