Task '&' has no agent assignment

What causes this issue?

Task '&v1&' has no agent assignment.

System Response

At runtime, no work item can be created for this task and the Workflow
is stopped.

How to fix this error?

To ensure that the modeled Workflow can be processed without errors, at
least one agent must be assigned to task '&v1&'.

Error message extract from SAP system. Copyright SAP SE.