How to solve Error: drive.google.com refused to connect?

This is a common error for Google Workspace users who are signed in to more than one Gmail account in the same browser. You click on the add-on and instead of its screen you only see a message that drive.google.com refused to connect. To fix this, use the add-on in an incognito window.

If you have signed in with multiple gmail accounts in your web browser and try to use any Google Workspace add-on, you might see this error: drive.google.com refused to connect. Please open an incognito window, sign in with your gmail account used to install the add-on (make sure that you haven't signed in with any other gmail account) and try to use the add-on. It should work.

The add-on works when you have signed in with only the gmail account used to install the add-on.

Summary

If you see drive.google.com refused to connect, the add-on is opening with the wrong Gmail account. With an incognito window, signed in with only the gmail account used to install Formfacade, the add-on should work. If you have any questions, write to support.