When you or your customers try to connect to Quickbooks Online, if you are seeing the following error message, this means that you have not completed the Quickbooks Online App Assessment Questionnaire.
'This app no longer meets our guidelines and standards. It's no longer available and you can't connect to it. Reach out to the app developer for support'
Quickbooks must have already emailed you the steps to complete the Quickbooks App Assessment Questionnaire.
Here you can find the steps that are needed to complete the Quickbooks App Assessment Questionnaire.