ArcGIS Server Manager is extremely slow and unresponsive

Description

ArcGIS Server Manager for the Microsoft .NET Framework is extremely slow and unresponsive, displaying "Object reference not set to an instance of an object" errors and not responding to requests.

Cause

The maximum number of worker processes in the Internet Information Services (IIS) Application Pool used by ArcGIS Server Manager is set higher than 1. This is a known limitation. The Application Pool setting for IIS must be set to 1.

This problem affects ArcGIS Server Manager for the Microsoft .NET Framework.

Solution or Workaround

In IIS Manager, verify the Maximum number of worker processes is set to 1.

1. Open IIS Manager from Administrative Tools on the Start menu.
2. Navigate to Application Pools.
3. On Windows 2003 Server (IIS 6), click DefaultAppPool and right-click to open the Properties. Click the Performance tab. In the Web garden section, verify the Maximum number of worker processes is set to 1.
   
4. On Vista or Windows 2008 Server (IIS 7), click Application Pools. Click Edit Application Pool and click Advanced Settings. In the Process Model section of the dialog box, verify the Maximum Worker Processes is set to 1.