IIS Application Host History Configuration
Applies To: Windows Server 2008 R2
The ApplicationHost Helper Service (AppHostSvc) maintains a history of Internet Information Services (IIS) configuration by saving the ApplicationHost.config file to separate configuration history subdirectories. If you make a mistake when you modify the ApplicationHost.config file, you can restore an earlier version of the file from a configuration history subdirectory by copying the earlier version into the %Windir%\system32\inetsrv\config directory. You can specify the frequency with which AppHostSvc checks for configuration changes, the path of the directory that contains the subdirectories, and how many subdirectories to keep.
By default, the Application Host Helper Service checks for changes in the ApplicationHost.config file every two minutes. If it detects that the configuration has changed, it creates a backup. The default location for the configuration history files is %SystemDrive%\inetpub\history. AppHostSvc creates one subdirectory under this directory for each configuration file backup. By default, the maximum number of history subdirectories is 10. If the number of configuration history subdirectories reaches the maximum specified, the oldest subdirectory is deleted.
AppHostSvc is a runtime-independent service that does not require the Windows Process Activation Service (WAS) or the World Wide Web Publishing Service (W3SVC) to operate. AppHostSvc does not depend on any other service and its startup type is Automatic. If the ApplicationHost Helper Service is stopped, the configuration history feature will not work.
Events
| Event ID | Source | Message |
|---|---|---|
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service encountered an error trying to process the configuration data for config history. The feature will be disabled. To resolve this issue, please confirm that the configuration file is correct, has correct attribute values for config history and recommit the changes. The feature will be enabled again if the configuration is correct. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service encountered an error trying to read configuration data from file '%1', line number '%2'. The error message is: '%3'. The feature will be disabled. To resolve this issue, please fix the configuration file and recommit the changes. The feature will be enabled again if the configuration is correct. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service encountered an error trying to read the property '%1' from configuration data from file '%2', line number '%3'. The feature will be disabled. To resolve this issue, please fix the property in the file and recommit the changes. The feature will be enabled again if the configuration is correct. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service encountered an error trying to delete the history directory '%1'. The directory will be skipped and ignored. Note that the directory may still get deleted in the future if the service restarts. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service encountered an error trying to access the root history directory '%1'. The directory either doesn't exist or the permissions on it don't allow the history service to access it. The config history feature is disabled for now and will be re-enabled after the issue is resolved. To resolve this issue, please ensure that the directory exists and that the Administrators group have read and write access to it. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The directory specified for the root history directory is a UNC path, which is not allowed. The feature will be disabled. To resolve this issue, please set it to a local directory. The feature will be enabled again if the configuration is correct. The data field contains the error number. | |
Microsoft-Windows-IIS-APPHOSTSVC |
The Application Host Helper Service has detected that %1 file doesn't contain valid configuration. Config history backup feature has been disabled. It will be re-enabled automatically once the configuration file is fixed. |