Renew Tokens When Using Safari
Renewing tokens with the checkSession() function does not work correctly with the latest version of the Safari browser.
Recent versions of the Safari browser introduced a new featured called Intelligent Tracking Prevention (ITP). ITP is designed to prevent websites from tracking user activity across multiple websites.
By default, ITP is active. You can determine if the Safari version you're using has ITP by going to Preferences > Privacy tab and seeing if the Prevent cross-site tracking option is checked.
ITP and Browser Behavior
Enabling ITP causes the browser to behave as if you'd disabled third-party cookies in the browser: checkSession() is unable to access the current user's session, which makes it impossible to obtain a new token without displaying anything to the user.
This is akin to the way OpenID Connect uses iFrames for handling sessions in single page applications (SPAs). Auth0 is working with OpenID Connect AB/Connect Working Group to determine if this issue can be addressed at the standards level.
There is currently no solution that will work with all use cases.
You can work around the issues posed by ITP by using Auth0s custom domains functionality, particularly if the custom domain lives on a subdomain of the application's website domain. For example, if your application is hosted on example.com, the custom domain would need to be of the format subdomain.example.com.