bypass validation error message

 I have set a DFF in the Ap invoice header, and select a lov of approver. but when the approver resign, i disabled it in the approval list, a customization form.

when query invoice with this approver inside the dff field will give a validation error message, somthing like approver xxx not exist in the [validation name ], user feels annoying

how do I hide this message and never show up when the approver in invoice is not active? can personlization achieve this? can anyone help me thanks!!