Issue: Some times workflow stops due to an error. It says 'Error updating a list item' and the outcome says 'Document checked out'.

Reason:
Document gets locked when there are multiple fields set from the workflow.

Fix:
Set the 'Checkout' action before the other action items in the workflow. After the updates, set the check in action. By wrapping the workflow actions with the 'check-out/check-in' actions document will be available for all the updates.