InstallationImpact enumeration

Defines the possible levels of impact that can be caused by installing or uninstalling an update.


typedef enum  { 
  iiNormal                     = 0,
  iiMinor                      = 1,
  iiRequiresExclusiveHandling  = 2
} InstallationImpact;



Installing or uninstalling an update results in a level of impact on the target computer that is typical of most updates. Therefore, the update does not qualify for any of the special impact ratings that are defined in this topic.


Installing or uninstalling an update results in an insignificant impact on the target computer.

The update must meet strict requirements to qualify for this rating. The requirements include, but are not limited to, the following requirements:

  • It must not perform or require a system restart.
  • It must not display a user interface.
  • The installation or uninstallation must succeed even if it affects an application or service that is currently being used.

Updates that qualify for this rating may be eligible for special handling in Windows Update Agent (WUA). For example, they may be eligible for accelerated distribution.


This update cannot be installed in the same IUpdateInstaller::Install or IUpdateInstaller::BeginInstall call as any other update. If you make an IUpdateInstaller::Install or IUpdateInstaller::BeginInstall call that includes an exclusive update along with one or more other updates, the call will return WU_E_EXCLUSIVE_INSTALL_CONFLICT, and no updates will be installed.


Minimum supported client

Windows XP, Windows 2000 Professional with SP3 [desktop apps only]

Minimum supported server

Windows Server 2003, Windows 2000 Server with SP3 [desktop apps only]