Ok. Let’s dig into this in more detail 
I appreciate that it can be frustrating when things don’t work as planned, but debugging is all about initially eliminating the obvious and then narrowing down on the specifics of the problem. Both of those are especially important when one is trying got do that remotely 
I am creating a MERN web App, where I am using login system through Auth0. While clicking login and choosing account I am getting an error page, Don’t know why this is happening. I have written almost exact code what tutorial has and still facing this error from last 2 days.
Firstly, can you share a link to the tutorial to which you’re referring?
Secondly, can you confirm whether the issue you’re experiencing is a result of integrating with the Auth0 front-end React SDK or the Express backend? In fact, if you are able to share the code you’ve written - always remembering to redact any security sensitive information - then that would be great. Thank you.