I have recently came across an issue that started occurring after updating .NET Framework in Windows Server. Here is the error message from Event Viewer:
SystemSource: Microsoft-Windows-WAS Event ID: 5172 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 errors below as well because Windows Process Activation Service fails to start. World Wide Web Publishing Service does not start too because it depends on Windows Process Activation Service.
Event ID: 7023Description: The Windows Process Activation Service service terminated with the following error: The data is invalid. Event ID: 7001Task Category: NoneLevel: ErrorDescription: 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 the configuration file is corrupted, IIS Manager will probably throw the error below:
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
Copy the.NET Framework IIS scheme file from the History folder to the path mentioned in the error message (C:\Windows\system32\inetsrv\config\schema\). Then restart IIS.
If you are still seeing this error, delete the xml file. Windows should create a new one automatically.