Just perform the following steps to display the real error happened in Sharepoint site instead of a generice Unknow error message.
- Backup your web.config of web application
- In SafeMode tag under SharePoint change
CallStack=”true”
MaxControls=”200”
After changing, your SafeMode node will be similar to following
<SafeMode MaxControls=”200″ CallStack=”true” DirectFileDependencies=”10″ TotalFileDependencies=”50″ AllowPageLevelTrace=”false”>
3. Set customErrors mode=”Off“