SharePoint Full Error Messages

While testing a SharePoint app, it is useful to see the "real" error messages instead of the nice "An unknown error occured. Please contact your system administrator".

As I'm always forgetting how to set the web.config to show the "real" errors, here are the couple of steps which need to be done:

1. Switch custom errors off
   

   <system.web>
   …
   <customErrors mode="Off" />
   …
   </system.web>

2. Enable CallStack
   

   <SharePoint>
   …
   <SafeMode CallStack="true" />
   …
   </SharePoint>