Diagnostic System Host (WdiSystemHost) Service Defaults in Windows 8

The Diagnostic System Host is used by the Diagnostic Policy Service to host diagnostics that need to run in a Local System context. If this service is stopped, any diagnostics that depend on it will no longer function.

Default Settings

Startup type:Manual
Display name:Diagnostic System Host
Service name:WdiSystemHost
Service type:share
Error control:normal
Object:LocalSystem
Path:%SystemRoot%\System32\svchost.exe -k LocalSystemNetworkRestricted
File:%SystemRoot%\system32\wdi.dll
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WdiSystemHost
Privileges:
  • SeChangeNotifyPrivilege
  • SeImpersonatePrivilege
  • SeTcbPrivilege
  • SeDebugPrivilege
  • SeAssignPrimaryTokenPrivilege
  • SeIncreaseQuotaPrivilege
  • SeProfileSingleProcessPrivilege
  • SeSystemEnvironmentPrivilege

Default Behavior

Diagnostic System Host is a Win32 service. In Windows 8 it will not be started until the user starts it. When the Diagnostic System Host service is started, it runs as LocalSystem in a process of svchost.exe, sharing it with other services. If Diagnostic System Host fails to start, the error details are added to Windows 8 error log. When the operating system startup is complete, the user is being notified that the WdiSystemHost service hasn't been started.

Restore Default Startup Configuration for Diagnostic System Host

1. Run the Command Prompt as an administrator.

2. Copy the command below, paste it into the command window and press ENTER:

sc config WdiSystemHost start= demand

3. Close the command window and restart the computer.

The WdiSystemHost service is using the wdi.dll file that is located in the %WinDir%\system32 folder. If the file is corrupted or deleted, you can put it back in there.