Serial number & cannot be used here

What causes this issue?

You have entered a <DS:GLOS.3526C31EAFAB52B9E10000009B38F974>serial
number</> already present in the system.

System Response

If this is an error message of type E:
The current serial number status means that you cannot assign the
serial number to the document (for example,
<DS:GLOS.3526C023AFAB52B9E10000009B38F974>material document</>,
<DS:GLOS.3526BEB2AFAB52B9E10000009B38F974>delivery note</>.
If this is an error message of type W:
You can assign the serial number despite the current status, or the
serial number has already been assigned. In this case, you should
verify the status and the causes of the error message.

How to fix this error?

Verify the status of the serial number using the function
<DS:TRAN.IQ03>Display material serial number</>.

Error message extract from SAP system. Copyright SAP SE.