Anyone developing on MOSS or WSS v3 is aware of how frustrating the useless error messages received in the interface can be ("Unknown Error Occurred"), and often these are not at all accompanied by a message in the ULS logs.
Here is how you enable more detailed error messages for your portal:
- Open up your sites web.config, and make the standard custom errors edit. You want it to be < customerrors mode="Off"/>
- Then, something a bit less obvious, search for the CallStack="False" and change it to CallStack="True", you should find this in the "<safemode>" node.
Thanks to Stefan Keir Gordon at www.keirgordon.com