We received notice on a server that the World Wide Web Publishing Service had stopped. This happened to be an Exchange 2010 server, so all webmail functionality stopped. I attempted to start the service manually but received an error that a dependency was unable to start. Reviewing the event logs, I saw that the dependency was the Windows Process Activation Service.

Unfortunately, the error was a bit unhelpful: “The Data is Invalid.”

As I scrolled through the event log, I came across another error that indicated what appeared to be corrupt XML data in a configuration file. This appeared as event 5172.

Sure enough, when I browsed to c:windowssystem32inetsrvconfigschema, the NetFX40_IIS_schema_update.xml file had been updated around the time webmail crashed.

Each time a change is made in IIS, Microsoft keeps a copy of the configuration files from before the change. Those can be found in c:inetpubhistory. From here, you will see a listing of configuration backups. In my case, I chose the latest copy and replaced the recently-updated version. After that, I attempted to start the World Wide Web Publishing Service, and it started right up!

Here is some more information about the Configuration History from Microsoft.