When opening the InventoryControl Web Module, if you receive an error page with the following messages:

 HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid.

Config Error: Cannot add duplicate collection entry of type 'add' with unique key attribute 'value' set to 'Login.aspx'

Config Source
   170:           <files>
   171:                  <add value="Login.aspx"/>
   172:           </files>

 there is an error in the web.config file.

To resolve this issue:

1. On the web server, browse to the path given in the Physical Path line of the error page.
   
   
2. Right click web.config and select Edit.
   
   
3. Find the <add value="Login.aspx"/> line, which will be almost at the end of the file, and insert a line in front of it with <clear/>, so those 4 lines will look like this:

             <files>
                      <clear/>
                      <add value="Login.aspx"/>
             </files>

Save the file, then go to Control Panel > Administrative Tools > Internet Information Services (IIS) Manager. Under Sites, click InventoryControlWeb. On the right side of the window under Manage Web Site, click Restart. Once it is restarted, the page should open properly.