What is your #1 pet peeve when onboarding a new vendor or supplier?

Suppliers not reading and following the process. Onboarding is an administrative activity, not a sales activity nor an upsell opportunity. 

Vendors who schedule an unsolicited meeting on your calendar.  Definitely a training opportunity for an EA is default never to accept a third party meeting without validating

To have clear communication and understanding between both parties. Ensuring that expectations, requirements, and terms are clearly defined from the outset can prevent misunderstanding and streamline the onboarding process. Verify the vendor's reliability, reputation, and adherence to relevant regulations is crucial to successful partnership.