My users complain about drive.google.com refused to connect error. How do I fix this?

If you are a G Suite addon developer and your users are complaining about "drive.google.com refused to connect" error, migrate your addon to apps script v8 engine. In the meantime, ask your users to sign in into one Gmail account at a time using incognito window.

1. How to solve this error permanently?

1. Open your Apps Script editor > Select View > Show project manifest.
2. In the appsscript.json manifest file, set the runtimeVersion field to the value V8.
3. Test your code for these migration incompatibilities: https://developers.google.com/apps-script/guides/v8-runtime/migration
4. Save it as a new version (under File > Manage versions) and deploy the new version in production.

2. How to solve this error while I am migrating to v8?

Share this article with your users that guides them step-by-step to solve this problem: https://formfacade.com/faq/error-drive-google-com-refused-to-connect-fix.html