Welcome to the Community. I'd be glad to help get you pointed in the right direction for assistance with fixing the "Business Validation Error: Unexpected Internal Error" that you received so you can get back to business.
Business Validation Error: Unexpected Internal Error usually occurs when QuickBooks connections need to be validated by the system. To get this fix, I'd suggest giving our Intuit Developer Team a call. They have the proper tools to check on your account and guide you thru the process of rectifying the issue.