Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561

I suddenly faced this error in my staging website.

Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

Problem is I created share folder for the website directory and windows 2008 removed the "Creator Owner" and "User" permission from the folder. After I added back these two permission, this error gone away.

My 2 hours of today is gone :{