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How to unload an application on IIS 6.0

(Kristofer Gafvert, October 8, 2005)

On IIS 5.0 you could unload an application from memory by clicking on the "Unload" button on the "Home Directory" tab of the website (or virtual directory) properties. If you try to do the same on IIS 6.0, you will notice that the button is always disabled.

This is actually by design. In IIS 5.0 a pooled process or isolated process was run within the dllhost.exe host process. The unload button can be compared to recycling the dllhost.exe process. IIS 6.0 introduced Worker Process Isolation Mode, and it would therefore make more sense to recycle the application pool (because that is where the application is loaded).

So why does the button still remain? The answer is simple, for backward compatibility. IIS 6.0 can be run in IIS 5.0 Isolation Mode, and in this case, the Unload button do have the same meaning as it had in IIS 5.0.

To recycle an application pool follow these steps:

  • In the left pane, select the application pool servicing the application, right click and click Recycle.
Recycle Application Pool

Recycling is better than starting and stopping the application pool. When stopping/starting the application pool requests may be dropped and the user presented with "Server not found" or "Service unavailable". Recycling (if overlapped recycling takes place) will allow all remaining requests to be processed and new requests will be directed to the new application pool. This means that the user should not notice any downtime.

Applies to [?]

IIS 6.0


IIS Process Recycling
Worker Process Isolation Mode (IIS 6.0)
IIS 5.0 Isolation Mode (IIS 6.0)
How Application Pools Work (IIS 6.0)