Authentication Error of /samples/vue/auth/authenticator

[tanshuai]

Describe the bug

I've tried many times with clean environment by following /samples/vue/auth/authenticator/README.md instructions to build Authentication using the Amplify Vue Authenticator Component.

BUT after npm run start the sample never work and always got "Authentication Error".

My other colleague had the same problem with /samples/vue/auth/authenticator/.

Our Amplify Console shows app backend is created and working by this sample project.

To Reproduce
Steps to reproduce the behavior:

1. Follow instructions from /samples/vue/auth/authenticator/README.md
2. npm run start
3. Open browser to http://localhost:8080/.
4. Try creating an account, resetting and signing in.
5. See Authentication Error.

Expected behavior

Create, Reset, Sign In with Amplify.

Screenshots

Desktop (please complete the following information):

• OS: MacOS
• Browser Chrome
• Version 91.0.4472.164 (Official Build) (x86_64)

Additional context
Add any other context about the problem here.