On an Internet Information Services (IIS) 7.0 server, you may see one or more of the following symptoms. In the system event log, you may see one or more occurrences of event ID 2297 from source Microsoft-Windows-IIS-W3SVC-WP and event ID 5172 from source Microsoft-Windows-WAS that resemble the following.
computer | Error | 10/27/2008 2:56:05 PM | Microsoft-Windows-IIS-W3SVC-WP | 2297
The worker process for application pool 'application pool id' encountered an error 'Configuration file is not well-formed XML ' trying to read global module configuration data from file 'path to the file', line number 'line number'. Worker process startup aborted.
Computer | Error | 10/27/2008 2:55:41 PM | Microsoft-Windows-WAS | 5172
The Windows Process Activation Service encountered an error trying to read configuration data from file 'path to the file', line number 'line number'. The error message is: 'Configuration file is not well-formed XML
'. The data field contains the error number.
Additionally, client requests may receive a response with status code 503 "Service unavailable."
You may see entries in the HTTP error logs with a status of "AppOffline."
Performing an IISRESET enables your Web sites to serve requests again.
This problem occurs because the configuration system reads the applicationHost.config file without locking it. If the IIS configuration file is being written to while the configuration is being read by the Windows Activation Service (WAS), the configuration may be inconsistent.
The following factors may make the problem more likely to occur:
A large (multi-megabyte) applicationHost.config file.
Frequent updates to the configuration (through direct modification of the applicationHost.config file or through one of the programmatic interfaces to the IIS configuration system (ABO, MWA, WMI).
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the “Hotfix Request” page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.
You must have Windows Vista Service Pack 1 or Windows Server 2008 installed to apply this hotfix.
You must restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfixes.
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.