Web.config Custom Errors mode Conflict

Question

I have a great and important problem with Web.Config, I need to see the Error of my page and resolve it in asp.net web form and web config, but when Error Occurred, I see an

Answer 1

When you're having issues with configuration, make sure that your settings isn't overridden.

In this case, your server might have a configuration that overrides application settings and disables trace output, custom errors, and debug capabilities.

Change the value to "false"

MSDN Link