Unable to retrieve ArcGIS install directory from registry

Error Message

When building a Web application in Manager or Visual Studio using the Web ADF for the Microsoft .NET Framework on a 64-bit operating system, the following error message may occur:

"Unable to retrieve ArcGIS install directory from registry."

Cause

The Web ADF for the Microsoft .NET Framework is unable to find the correct registry values, because it requires an application pool that is running in 32-bit mode and not 64-bit mode.

Solution or Workaround

Note:
Modifying an existing application pool to support 32-bit applications could potentially impact other Web applications running in that application pool.

1. Click Start > Administrative Tools > Internet Information Services (IIS) Manager.
2. Navigate to the tree view in IIS to determine where the Manager application is installed. Typically, this will be under the Default Web Site in the ArcGIS folder.
   
   
3. Determine the application pool that Manager is currently running in by right-clicking Manager in the tree view and selecting 'Advanced Settings'.
   
   Typically, Manager will be running in the default application pool called DefaultAppPool.
   
   Once the name has been determined, click Cancel to dismiss the dialog box.
4. In the tree view on the left, select Application Pools. In the list that is displayed, right-click the application pool that Manager is currently running in and select 'Advanced Settings'.
   
   
5. In the 'Advanced Settings' dialog box, locate the property 'Enable 32-Bit Applications' and set it to True. Click OK.
   
   
   

   Note:
   If Visual Studio is being used to create Web applications with the Web ADF, ensure that the Web applications also use an application pool that supports 32-bit applications.