Anyone have insight in why this would all of a sudden show up and/or how to resolve? Luckily, this is in a sandbox environment.
The client was trying to create a new sales order and this is occurring now when they are in the sales order, enter a customer, and tab to the next field.

I do notice that they have a sales order that is number ' and I've tried to delete and it won't remove. Could this also be the culprit?