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Event ID 5191 — IIS Application Host Helper Service Availability

  • Article

Applies To: Windows Server 2008 R2

The Internet Information Services (IIS) Application Host Helper Service requires access to a directory in which it can store temporary configuration files that it creates at run-time for application pools. The directory must be available to WAS and cannot be on a UNC path. If these conditions are not met, the Application Host Helper Service SID mapping functionality may be unavailable.

Event Details

Product: Internet Information Services
ID: 5191
Source: Microsoft-Windows-WAS
Version: 7.5
Symbolic Name: WAS_ISOLATION_PATH_UNC_ERROR
Message: The directory specified for the temporary application pool config files is a UNC path, which is not allowed. Please specify an existing local directory instead. The data field contains the error number.

Resolve

Check the temporary application pool configuration directory

The Windows Process Activation Service (WAS) generates temporary application pool configuration files that it stores in the %SystemDrive%\inetpub\temp\appPools directory by default. If you change this location, WAS may not be able to find the directory.

To resolve this issue, make sure that the appPools directory meets the following requirements:

  • The directory must exist.
  • The directory cannot be on a UNC path.
  • The directory must be available to WAS and should have the following permissions:
    • SYSTEM: Full Access
    • Administrators: Full Access
    • IIS_IUSRS: Read

Verify

To verify that the Application Host Helper Service is running correctly, you can do the following:

  • Use the command line to verify that the service is running (see Section I).
  • Make a token change in the ApplicationHost.config file, then check the configuration history directory to verify that a configuration backup was made (see Section II).

To perform these procedures, you must have membership in Administrators, or you must have been delegated the appropriate authority.

I. Use the command line to verify that AppHostSvc is running

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type sc query apphostsvc, and press ENTER. The Application Host Helper service is running if the state reported for the service is 4 RUNNING.

II. Verify that configuration backups are being created

A.  Make a token change in ApplicationHost.config.

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type cd %Windir%\system32\inetsrv\config.
  3. Type notepad ApplicationHost.config.
  4. On the second line of the file, after the beginning "<!- -" comment mark, add some text such as "Configuration History Test".
  5. Save the file and note the time of the change. Because you have added a comment to the configuration file, AppHostSvc will detect the change and make a backup, even though no change to configuration itself has been made.
  6. Close notepad.

B.  Check to see whether a configuration backup was made.

By default, the location for the configuration history files is %SystemDrive%\inetpub\history. AppHostSvc creates one subdirectory under this directory for each configuration file backup. The configuration history subdirectories are named in the format CFGHISTORY_serialnumber, where serialnumber is a 10-digit sequential number (zero padded).

  1. At the elevated command prompt, type cd %SystemDrive%\inetpub\history.
  2. Type dir. A list of the configuration history subdirectories appears.
  3. Note the date and time of the most recent CFGHISTORY directory. By default, AppHostSvc checks for changes in the configuration files every 2 minutes. If you have not changed the value of the configHistory period attribute, a new CFGHISTORY directory should appear within 2 minutes of the time that you noted in part A.
  4. Type cd CFGHISTORY_serialnumber  to open the new directory.
  5. Check the date and time of the ApplicationHost.config file inside the CFGHISTORY directory. The file timestamp should be within 2 minutes of the time that you noted in part A above.

IIS Application Host Helper Service Availability

Internet Information Services (IIS) 7.5