Sometimes this happens to users with multiple Gmail accounts on a site that uses Login with Google - a plugin by Dan Lester.

Users sometimes can’t login because Google chooses their personal Gmail account

Here’s what happens whenever you click Login with Google, and it depends how many Google accounts are currently logged-in within the same browser:

  1. If currently logged in to 0 Google accounts, you will be asked to login to one and the plugin will attempt to login to WordPress against that account
  2. If currently logged in to exactly 1 Google account, Google will automatically return that account for the WordPress login attempt
  3. If currently logged in to 2 or more Google accounts, Google will show the user a list of current accounts and allow them to choose which one they want for the WordPress login

Then, if the selected Google account doesn’t match an existing WordPress account and doesn’t come from a Google Apps domain that is authorized in the plugin to have a WordPress account created for it, the user will be told:

Email address needs to be in is not authorized – Sign out of Google to switch accounts

If this is causing confusion, one possibility is to tick the option in Advanced Options of Settings -> Google Apps Login labelled ‘Force user to confirm Google permissions every time’. This adds an extra step to everyone’s login flow asking them to confirm they are happy for Google to connect to the WordPress site (by default, they only see this the very first time). The only reason for this option is to give the user a chance to see (in the top right corner) which Google account has been picked up, and give them the opportunity to change it.