If you get the Oops error message, it's most likely that QuickBooks has disconnected from our app and you will need to reconnect. This can happen for various reasons including the fact that QuickBooks policy is to disconnect all apps after 12 months and force a reconnection.
To fix this error Login to our app > https://shuttleglobal.com/apps
Next click on QuickBooks and on the following screen press the RECONNECT button.
You should be all set now.