Sometime you need to set up a custom identity for IIS6 application pools, but if you directly do that, you may receive the following errors in event log.
Event Type: Warning
Event Source: W3SVC
Event Category: None
Event ID: 1021
The identity of application pool, 'xxx' is invalid. If it remains invalid when the first request for the application pool is processed, the application pool will be disabled. The data field contains the error number.For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
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Error code 0x80070569 means "Logon failure: the user has not been granted the requested logon type at this computer."
The right approach to setup a custom identity for IIS6 application pool is below,
1. Create the service account and set the password cannot be changed and password never expire.
2. Add the service account to IIS_WPG group.
3. Go to local policy - user rights assignment, add the user to "Log on as a service".