Overview:
When completing a task, the user gets an error message:
The document must have the following criteria for the workflow to continue: The workflow task assignee group Owner must contain users.
Root Cause:
The Owner of the document changed while the workflow was still active. An internal process needs the previous owner of the document to continue the workflow.
Solution:
You need to assign back the Owner role to the user who was the Owner when the workflow started. Check in the Audit Trail the changes in the Owner role and in the Workflow Timeline when the workflow started to be able to identify the right user to assign the Owner role. Then proceed with workflow completion.
If the Owner is inactive you will need to activate it back to proceed, or cancel the workflow.
Related Documentation:
Vault Help Documentation: N/A