Helping people with computers... one answer at a time.

"The Windows Installer Service could not be accessed" is a frustrating error with many causes. I'll look at one trick that may clear a few of them up.


My OS is Windows Vista. Every time when installing a program that uses Windows Installer, I receive a message like this: “The Windows Installer Service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance. ” Do you know any reason why this is happening and what have to be done?

Unfortunately, the situation can occur for several different reasons - some of which are understood and some of which are not.

As a result, I don't have the answer, but...

I do have something to try. Something that I have heard that can help get past the situation in many cases and should work in Windows XP, Windows Vista, and Windows 7.

The theory

The theory is that the Windows installer has become confused somehow by the previous installation. Perhaps that installation crashed, perhaps the installation was aborted, or perhaps it simply finished and failed to finish cleanly. Regardless, the Windows installer is in a confused state and unwilling to accept further installations.

“...this may not fix every Windows installer 'could not be accessed' problem, but it's a simple trick that can clear many confused situations.”

One approach to clearing the confusion is to, for lack of a better term, "whack it upside the head" by turning it off completely.

Disable the Windows installer service

Right-click on Computer or My Computer, click Manage, expand Services and applications, then click Services.

Manage Computer Services

In the list that appears to the right, scroll down until you see Windows Installer. Right-click on that and then click on Properties.

Windows installer service properties

The Startup type listed will be either manual or automatic.

Change it to Disabled and click OK.

Reboot your computer.

Re-enable the Windows installer service

Repeat the steps above, but this time, change Startup type from Disabled to Manual.

You do not need to reboot your computer here.

Now, try installing something and see what happens.

The theory is that forcing Windows to restart with the Windows installer service disabled causes some of the confusion about its state to be reset.

And once reset, Windows installer can be used again.

As I said, this may not fix every Windows installer "could not be accessed" problem, but it's a simple trick that can clear many confused situations.

Article C4915 - August 27, 2011 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

August 30, 2011 8:46 AM


What do you think of the "Windows Installer Cleanup Utility"? I've been using it occasionally for years to fix the sort of problems described. Microsoft doesn't carry it any more but its available free of charge from other sources.


I two found it useful, but Microsoft stopped carrying it because apparently it occasionally caused problems.

David Cashin
August 30, 2011 9:45 AM

The windows installer clean-up util, msicuu2.exe seems to be current with vista & 7. David C.

Apparently not. To quote the Microsoft website: "While the Windows Installer Cleanup utility resolved some installation problems, it sometimes damaged other components installed on the computer. Because of this, the tool has been removed from the Microsoft Download Center."

Bernard Winchester
August 30, 2011 2:15 PM

I heard it was withdrawn because it occasionally has damaging effects, but it has worked for me in the past.

September 1, 2011 7:26 AM

I had this exact problem a few weeks ago and spent Daaaayyyyys with I.T. over the issue. Finally they were going to re-image my machine.

I spent five minutes on an internet search and found this:

windows installer needs to be re-registered.
1. open a command prompt:
2. Type msiexec /unregister and press Enter.
3. Type msiexec /regserver and press Enter.
this re-registers your windows installer.

Worked like a charm!

September 1, 2011 9:50 AM

I can,t believe that some people are still using Vista ! Dump it and move on~ download Ubuntu 11 for free and see your computer come alive.

September 5, 2011 7:24 AM

Thanks but i like add one more thing, you did not mention start service status option.

September 5, 2011 8:59 AM

"I can,t believe that some people are still using Vista ! Dump it and move on~ download Ubuntu 11 for free and see your computer come alive."

Sure, if you can understand it and have a PhD. in computer skills. I like what Ubuntu has done, but I don't think it's ready for Grandma yet, the test of a real desktop system. My last trial of it, I had to open the command line too often to install what I wanted, and the boot loader somehow h0sed my system, and I had to format the whole hard drive, in the process h0sing my recovery partition. Had I not made a recovery DVD.... well.

My machine came pre-installed with Vista, and I love it! I haven't had ANY of the problems described by people who tried to install it over XP (or ME???); the machine just runs, is reliable, and I only paid about $300 US new! (2.2 Ghz dual core Athlon 64X2, 2 Gb DDR2, 320 Gb SATA, Windows Vista Home Premium.) I have been amazed since I got it, and like it at least as well as my wife's laptop with Win 7.

When new computers start shipping with Ubuntu and an emulator (so I can play my few Windows games I enjoy), I will think about it. For now, I'll "dance with the one that brung me".

October 25, 2011 4:26 AM

This error can occur if the Windows Installer tool is damaged.

Please click the link below for ways to fix it:

January 27, 2012 3:55 PM

This was the second time in two years that I have experienced problems with Windows Installer and I am very pleased to find, again, the solution to my problems; many thanks Leo.

March 19, 2013 11:21 PM

I tried to use the method described above but I do not have the option to change the startup type. As I am the only user and the administrator, I do not know why.

Note: I'm running Windows 8

Mark J
March 20, 2013 2:46 AM

I had that problem, and tried Leo's solution. It worked, and it wasn't necessary in my case to reboot. So you might try and see if it works without rebooting first to save time.

Simon B
March 28, 2013 8:34 AM

Your fix didn't work for me, (thanks for trying) but this one did:

[Copyrighted content removed]

(copied from )

April 20, 2013 4:18 PM

I don't have the option to switch it from manual to disabled, its grayed out and doesn't give me the option to click and change the setting.

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