ASP.NET ASPX Debugging

What's the best way to systematically debug the aspx pages ( not C# or Vb.NET managed code). Sometimes a small syntax or semantic error in aspx page displays:

Internal server error or something similar

and I had to comment the last changes step by s开发者_运维技巧tep to find out the error.

Is there any other systematic way of doing this?

This post might help (however you should remember to switch the application into Release mode before launching it on the production environment).