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Cannot Select an Application Pool in IIS 6.0 "Invalid Application Pool" message

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Problem Description

When trying to configure an Application Pool for a web site or web Application you see <Invalid Application Pool> in the Application Pool field on the Home Directory tab of the properties of the Site or Virtual directory. There may be other application pools to select or there may not.

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There are no errors in the system event log.

 

Cause

This problem occurs when the KeyType element is missing or contains an invalid
string. A list of possible values for this element is available in MSDN.

 

Resolution

Method #1

Use adsutil.vbs to identify the Application pool which does not show up in the MMC

Enumerate the application pools:

C:\Inetpub\AdminScripts>adsutil.vbs enum /p w3svc/apppools [/w3svc/apppools/DefaultAppPool] [/w3svc/apppools/ASP.NET 1.1] [/w3svc/apppools/ASP.NET 2.0] [/w3svc/apppools/Broken App Pool] [/w3svc/apppools/Kerberos] C:\Inetpub\AdminScripts>

Then get each app pool keytype, we are looking for one which either returns "The Parameter 'keytype' is not set at this node" or returns a string which is NOT "IIsApplicationPool"

C:\Inetpub\AdminScripts>adsutil.vbs get "w3svc/apppools/Broken App Pool/keytype" keytype : (STRING) "IIsApplicationPoolNOT" C:\Inetpub\AdminScripts>

Once you have identified the invalid application pool you need to correct or add the value for keytype.

C:\Inetpub\AdminScripts>adsutil.vbs set "w3svc/apppools/Broken App Pool/keytype" IIsApplicationPool keytype              : (STRING) "IIsApplicationPool" C:\Inetpub\AdminScripts>

Method #2

You can also use Metabase Explorer to correct this issue. Metabase Explorer is part of the IIS Resource Kit Tools.

  1. Open MB Explorer.
  2. Expand LM>W3SVC>AppPools.
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  3. Look for application pool which does not show up in IIS MMC or one missing or with an invalid string value. The only valid value at this location is "IIsApplicationPool".
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  4. Add a Record called "KeyType" with a value of "IIsApplicationPool".
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  5. Close Metabase Explorer.
  6. Open IIS MMC and should be able to change application pool on web site/virtual directory now.

Technorati Tags: IIS 6.0,Metabase.xml