Problem statement
This post addresses the situation in which the login page is sometimes not loading when using Classic Universal Login.
Solution
For the universal login page to load, make sure that the “Lock” javascript file loads successfully.
The classic universal login script should have a line similar to this one, depending on the current version:
<script src="https://cdn.auth0.com/js/lock/12.3/lock.min.js"></script>;
It’s possible to check in the browser network developer tools if this file is loading or not. If it is not, please make sure from the network that it is possible to access the auth0 cdn or try using the link above directly. It is also possible to check incidents on the auth0 status page related to cdn network issues.