ASP.NET Tutorial/Configuration/customErrors
Custom Error Messages
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.web>
<customErrors
mode="On"
defaultRedirect="Default.aspx"
/>
</system.web>
</configuration>
Disable custom errors
File: Web.Config
<configuration>
<system.web>
<customErrors mode="Off" />
</system.web>
</configuration>