Frontend printing already in process

What causes this issue?

Frontend printing already seems to be running. The server cannot be
called a second time.
If nothing is printing, there may be a remaining lock entry.

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?

Procedure for System Administrators

Delete lock entry in table TSP02F.

Error message extract from SAP system. Copyright SAP SE.