Here is the guide to enable the detailed error, within IIS 7.0
First of all, you need access to IIS controlpanel, and the Webconfig from the specific website, you want's to see the detailed error from. In the Webconfig, it's very important that you have specified the CustomError mode to Off, otherwise your local configs would overwrite the server default settings. Please check you got the same setup as the example below.
<customErrors mode="Off" />
If you still receive the default error, you have to change the server custom error module settings. You can do this from the IIS7 Admin tool by running the server manager, or writing inetmgr.exe from the Run command.
- Select your website, at the left menu
- Click on the "Error Pages" button
- Click on the action "Edit Feature Settings" at the right menu
- Pick the "Detailed errors" option
- Confirm the change by clicking "OK"
You should now be able to see the detailed error from the IIS7 webserver, from your remote location. Check the picture below, to verify you got the same settings.