How To Fix WL321 - Background work item no. & could not be started: runtime error?

SAP Error Message - Details

• Message type: E = Error

• Message class: WL - Workflow: run-time messages

• Message number: 321

• Message text: Background work item no. & could not be started: runtime error?

What causes this issue?

Background step no. &V1& was created (status: <ZH>ready</>), but has
not been started (transition to status: <ZH>in process</>.

System Response

Workflow no. &V4& has stopped without this being noticed.

How to fix this error?

The cause of the problem may be one of the following:
The transactional RFC call for starting the background step failed or
is still waiting for its execution. In particular, when there is a high
burden on the system this can delay the calling of the background step.
Check the RFC queue (<DS:TRAN.SM58>transaction SM58</>) and the
Customizing of the workflow system (<DS:TRAN.SWU3>transaction SWU3</>).
The workflow system crashed when the background step was started.
Analyze the system log (<DS:TRAN.SM21>transaction SM21</>) or any dumps
(<DS:TRAN.ST22>transaction ST22</>).
More information may be obtained by using the diagnostic utilities in
SAP Business Workflow.
If this message is still displayed after 30 minutes in the Workflow log
and you cannot solve the problem yourself, contact the workflow system
administrator responsible.

Error message extract from SAP system. Copyright SAP SE.