Enable Detailed Errors

How to enable detailed errors (ColdFusion, Railo, .Net) on IIS 7+ (Windows 2008 and 2012)

• Edit or create the file web.config within the folder in which detailed errors should be enabled.
• Add the following:

<configuration>
   <system.webServer>
      <httpErrors errorMode="Detailed" />
   </system.webServer>
</configuration>

NOTE: If any of the above sections already exist in the web.config" file, edit the existing sections. Do not duplicate.

• To re-enable custom errors (or non-detailed errors), update the web.config file changing the errorMode attribute from Detailed to Custom.