I've got workflows that need to restart the approval process if an approved invoice and vendor bill (no credit or payment yet) is edited. Basically, the approval status would change from Approved to Pending Approval. It works perfectly for Vendor Bills but I get this error for Invoices: "Approved Invoice cannot be set to Pending Approval or Rejected status." Is that not possible for invoices?

Luis, do you have any scripts/integrations running on invoices?

None. Just that workflow

Theoretically if your original workflow is a persistent one (doesn't end) then it would throw error when another workflow tries to set the approval status field.

When you say persistent, is it when you check the Do No Exit Workflow box? If so, I didn't do that or no other workflows do that.