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?

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