If you have done any MOSS or WSS 3.0 customization at all, then you have definitely seen the painfully worthless "Unknown error occurred".
I highly recommend that these couple of minor web.config changes be added to all development sites and temporarily added to any live sites that you are seeing this wonderful message.As with any ASP.NET 2.0 application, you can turn off the custom MOSS error page by changing the customErrors mode="On" to "Off": <customErrors mode="Off" />
You can also turn on the call stack by changing the CallStack value from "false" to "true" in SafeMode: <SafeMode MaxControls="200" CallStack="true" DirectFileDependencies="10" TotalFileDependencies="50" AllowPageLevelTrace="false">
Thanks to Andrew Connell and Shane Perran for providing this info.
