Specify server group for parallel processing

What causes this issue?

You want to start parallel processing, but the system needs a server
group.

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?

Enter the server group for parallel processing in the corresponding
field of the selection screen.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.