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Go to Project Settings and select Edit for the workflow you want to edit.
Select the transition where you want to add the validator. In this case, we will choose the In progress transition.
Go to the Validators tab, and select Add validator.
Select the Fields Required (JSU) validator then select Add.
Now you can configure your validator. Select a field from the Available Fields list, then select Add to add it to the Required Fields list. Here, we added Assignee and Due date.
Select Add at the bottom of the page.
Publish your workflow.
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