Microsoft releases Windows updates every second Tuesday of the month. Most of the time, these updates require a restart. Therefore, you may see some unexpected behavior the very next day of the updates and restart. The issues are not necessarily caused by Windows updates. Sometimes, a past configuration change takes effect after the updates because the machine is restarted.
In this post, you will find information about an issue that came out after updating .NET Framework in Windows Server.
Error message (Event ID 5172)
Here is the error message from Event Viewer:
SystemSource: Microsoft-Windows-WAS
Event ID: 5172
Task Category: None
Level: Error
Keywords: Classic
Description: The Windows Process Activation Service encountered an error trying to read configuration data from file 'C:\Windows\system32\inetsrv\config\schema\NetFx40_IIS_schema_update.xml', line number '1'. The error message is: 'Configuration file is not well-formed XML'. The data field contains the error number.
You may see the following errors as well because Windows Process Activation Service fails to start. World Wide Web Publishing Service fails as well since it depends on Windows Process Activation Service.
Log Name: System Source: Service Control Manager Event ID: 7023 Task Category: None Level: Error Keywords: Classic Description: The Windows Process Activation Service service terminated with the following error: The data is invalid.
Log Name: System Source: Service Control Manager Event ID: 7001 Task Category: None Level: Error Keywords: Classic Description: The World Wide Web Publishing Service service depends on the Windows Process Activation Service service which failed to start because of the following error: The data is invalid.
Since this configuration file is corrupted, you probably won’t be able to use IIS Manager:
In addition to this xml error, if your application pools are disabled, I recommend checking this post out: HTTP 503 Service Unavailable (Application pool has been disabled)
Solution for NetFx40_IIS_schema_update.xml error
The good news is that Windows backs up IIS configuration files before making any changes to them as part of Windows updates. NetFx40_IIS_schema_update.xml is one of these files.
Backup folder is C:\inetpub\history
In order to solve this issue, copy the last good of .NET Framework IIS scheme file (NetFx40_IIS_schema_update.xml) to the path mentioned in the error message (C:\Windows\system32\inetsrv\config\schema\). Then restart IIS.
Still seeing the error?
If you are still getting this error, try deleting the xml file. Windows should create a new one automatically. This post mentions that this workaround worked.
If you are using Shared Configuration in IIS, the root cause of the issue might be different than what I mentioned above (Windows updates). There might be an issue with file synchronization. For more details, check this post out: Configuration file is not well-formed XML (IIS Shared Configuration)
