Could not load file or assembly AjaxControlToolkit…


Cause: This error occurs in Overwatch when the SystemOverview.aspx is browsed to. This error means there is an issue with the version of .NET Framework running on the AppServer.

Resolution: To resolve this issue follow the steps below:

  1. For IIS 6.0:

a)      Open IIS.

b)     Right click on your virtual directory for Overwatch.

c)    Click properties.

d)   Click on the Virtual Directory tab.

e)   Under the Application Settings section, locate your Application Pool.

f)    Expand your Application Pools folder.

g)   Verify that the Application Pool for your Virtual Directory is using .NetFramework 4.0.


For IIS 7.0:

a)Click on your Virtual Directory.

b)Select Advanced Settings in the right hand pane.

c)Find your Application Pool name.

d)Click on the Application Pool icon on the left hand pane.

e)Locate your Application Pool being used by your Virtual Directory.

f)Verify that the .NET Framework is 4.0.


  1. If .Net Framework 4.0 is not installed try re-installing it.
  2. If .Net Framework 4.0 is installed, change the .Net Framework version used by your Application Pool to 4.0.
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