Windows Service Pack Blocker Tool is a package of a Microsoft-signed executable, a script and an ADM template (for Group Policy environment) that allows Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R users to block and prevent installation of respective Windows Service Pack updates through Windows Update or Automatic Update.

There are several reasons why you may want to block and prevent automatic update of service pack or user ability to install service pack via Windows Update, especially for administrators. Just imagine if your company has thousands of PCs and notebook computers, and all of them is downloading the large service pack concurrently. It not only wasting network bandwidth, but will not slowdown Internet performance. Beside you may also want to evaluate the reliability and performance of service pack before rolling out in your organization. Or you simply just want to hear some reviews first, letting others become Guinea pig (but that’s not the case with Vista SP1 though, which promise huge performance, reliability and compatibility increase, thus which should be installed as soon as possible).

Whichever component of Windows Service Pack Blocker Tool you use, the function is the same, that is to set or clear a specific registry key that is used to detect and block or unblock (the default action without key, unless you have blocked the SP update, else no need to do anything to get the service pack installed on your computer) delivery download of Windows Service Packs from Windows Update to the target computer. The registry key involves is:


When blocked, a key value named DoNotAllowSP will be created and has the value of 1. When configure to allow service pack to install on the comptur, the key is removed. If you’re single home user, you can set the key manually using Registry Editor without downloading the toolkit if you want to block the installation of any service pack.

The additional advantage of script is that users can specify the remote machine name on which to block or unblock delivery of Windows Service Packs, saving considerable time by eliminating the need to go to physical computer location.

The best thing is that, even though the service pack blocking registry key is set, the toolkit will not prevent the installation of the service pack from CD/DVD, or from the stand-alone download package. Thus once administrator decided to distribute and roll out service pack locally, it can be installed without unset the block.

Windows Service Pack Blocker Tool can be used to stop, block and prevent the following service pack as below. The blocking works for a period of time only, of which once expire will automatically invalidate itself.

  • Windows Server 2003 Service Pack 2 (valid through March, 2008)
  • Windows XP Service Pack 3 (valid for 12 months following general availability)
  • Windows Vista Service Pack 1 (valid for 12 months following general availability)
  • Windows Server 2008 Service Pack 1 (valid for 12 months following general availability)
  • Windows 7 Service Pack 1 (valid through 2/22/2012)
  • Windows Server 2008 R2 Service Pack 1 (valid through 2/22/2012)

Download Windows Service Pack Blocker Tool Kit: SPBlockerTools.EXE.

Update: The utility on longer blocks any service packs and beginning from Windows 8 and Windows Server 2012, Microsoft has essentially eliminates service packs.