Serial number management only allows whole numbers

What causes this issue?

For this material, serial number management is active. This means that
you have to maintain a <DS:GLOS.serial_number>serial number</> for each
individual part. Decimal places are not possible in conjunction with
serial number management.

System Response

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?

Change the specified quantity.

Error message extract from SAP system. Copyright SAP SE.