In IIS 7, you can control the detailed ASP error messages being sent to the clients. By default, the error messages are disabled from being send to users in order to prevent exposing more information than you intended to show.  Read article on How to Use HTTP Detailed Errors in IIS 7.0 for more information. If you want to enable detailed error messages to be shown on the users for the development or debugging purposes, then you need to make the two following adjustments in the IIS7 Manager:

a) Allow showing error messages for local requests:

  1. Connect to your server using IIS7 manager.
  2. In the Features view, double click ASP.
  3. Expand Debugging Properties, set Send Errors To Browser to True, and click Apply.

b) Allow sending detailed error messages for remote requests (not required for Dedicated Web Hosting accounts):

  1. Go back to IIS7 modules.
  2. In the Features view, double click Error Pages.
  3. Right click and select the Edit Feature Settings… for any specific error code or select the same from the Actions pane.
  4. Select the Detailed errors radio button and click OK.

Note: It is recommended to change the settings back when development/debugging is complete.

Note: Internet Explorer does not show proper error messages by default. To enable friendly HTTP error messages in Internet Explorer:

  1. On the Tools menu in Internet Explorer, click Internet Options.
  2. Click the Advanced tab.
  3. In the list of options under Browsing, clear the Show friendly HTTP error messages check box.
  4. Click Apply, and then click OK.