This error is due to the connection to Sage 50 has become de-authorized; so the connection becomes invalid.
To fix this issue you would need to follow these steps:
- Navigate to the integrations page of Receipt Bank and where the current integration is displayed (Sage 50) and click on the blue 'change' button
- On the next screen click on the red 'disable integration' button
- Then the connector needs to be uninstalled. This can be done by finding the connector in the task bar, right-clicking on it and selecting uninstall
- Finally Sage 50 needs to be re-integrated by following the instructions here