ISSUE
The following error might appear when you attempt to sign in via centralized login:

signin.webex.com supports login for various Webex services. However, it does not cover all Webex products. Also, it's important to know that this site does not support login functionality for Single Sign-On (SSO) or accounts without email address verification.

RESOLUTION
If you're using a supported account and still encountering difficulties, consider the following steps:

1. Confirm that you're inputting an email address instead of a username.
2. Attempt to access your account directly (e.g., https://SITENAME.webex.com).  Remember to replace 'SITENAME' with your actual Webex site's name.
3. Please review the 'Webex | Reset Your Forgotten Password' guide to reset your password.