There was a problem with your log in: There is a user with the same email….

[I posted this in the Auth0 Community forum yesterday…]

We have integrated Auth0 with the plugin. Everything has been working for weeks now – first in development, and then launch last week. Two days ago a couple of users received this error when trying to log in:

“There was a problem with your log in: There is a user with the same email. [error code: unknown]”

This error appears to be coming from the WordPress site – the message looks like a standard WordPress error message, and the user history in Auth0 shows a successful log in. No errors are reported in the PHP error log on the WordPress site.

The only way I’ve been able to resolve the issue for these clients has been by deleting and recreating their accounts (both WordPress and Auth0).

But now many more users are running into this problem (both brand new users, and ones who have been using the tool for a few days) AND the fix of deleting and recreating their accounts is no longer working. Of course, I have not been able to recreate the error with my own test accounts, only with accounts for users who have reported the problem.I have compared the sizes of working accounts and the problem accounts and don’t see a difference (a suggestion from another discussion).

Once this has happened with a log in (successful Auth0 log-in, unsuccessful WP log-in), the user gets the error message as soon as they attempt to access the Auth0 login page, and this persists through browser reboots. So Auth0 sees the logged-in status and bounces the user over to WordPress, but there the error appears. Private browser windows will allow folks to attempt to log in, but the same error appears. So too with navigating to the auth0 site and clearing all cookies — that allows the login window to appear, but the error repeats if we try to log in.

The only thing that has changed is that on Friday we moved up to a paid-level account with Auth0. But everything was working fine for a couple of days after that, and most users are still able to log in without a problem.

I’ve double-checked the set up instructions “Configuration of the Login by Auth0 WordPress Plugin” in the Auth0 docs. I didn’t find any problems, and re-applying the settings didn’t make a difference.

Wordpress vs 5.3.2
Auth0 plugin 4.0
PHP 7.1.33

I’d appreciate any help. Thanks!