The value & is not allowed for the field &

What causes this issue?

When you transfer data by <DS:GLOS.direct_input>direct input</> or when
you distribute data by <DS:GLOS.Application_Link_Enabling>application
link enabling</> (ALE), the system performs the same checks as in
online mode. However, the value &V1& is not allowed for the field &V2&.

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?

Check what values are allowed for the field in online mode.

Error message extract from SAP system. Copyright SAP SE.