On Error steps
An On Error step detects errors so you can take remedial action if one occurs. For example, a remedial action might be to send an email notification to a user if a file failed to upload. An On Error step must be attached to the action step you want to monitor—in this example, a file upload.
When you choose On Error from a flow step's options menu, you are prompted to configure a new action, beginning with choosing an app or utility for the remedial action.