Number of update2 work processes

What causes this issue?

Technical constraints:
There does not necessarily have to be any work processes of the Update
2 type (low-priority update). However, as high-priority updates could
be delayed without them, we recommend that you configure at least one
work process of the Update 2 type for each system.
You can set the number of these work processes using the system
parameter <ZH>rdisp/wp_no_vb2</>.
For more information about this topic, see SAP Note 39412 (How many
work processes to configure)

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.