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I am having a problem installing iTunes on my Windows 7 laptop. When I tried to run the application I got this message:

The Windows Installer Service could not be accessed. This can occur if you are running Windows in safe mode, or the Windows Installer is not correctly installed. Contact your support personnel for assistance.

Now I am not running it in safe mode, and I am the administrator on the laptop.

I made sure the Windows installer was running through the services.msc.

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migrated from Sep 30 '12 at 23:59

This question came from our site for professional and enthusiast programmers.

Have you installed anything else and not rebooted in between? – Nicole Hamilton Oct 1 '12 at 0:00
Two things you can do.First, check "system restore" and see if you had any point where something major was installed so you can revert back to it and try again. Second, if that doesn't work, use your windows install cd and perform a repair. Remember if you perform a repair, all your drivers are reset. – AlanTuring Oct 1 '12 at 1:14

I got the error "Windows Installer Service could not be accessed" installing a different program, but the fix should be the same.


These instructions are for 64-bit Windows 7:

  1. Open a command prompt

  2. Run %windir%\system32\msiexec.exe /unregister

  3. Run %windir%\system32\msiexec.exe /regserver

  4. Run %windir%\syswow64\msiexec.exe /unregister

  5. Run %windir%\syswow64\msiexec.exe /regserver

  6. Close the command prompt and reboot

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Great answer! I had a similar problem with another installer and general problems both installing and uninstalling (but the exact same error message). This answer saved me reinstalling Windows! – Peter Mortensen Jul 30 '15 at 18:13

Try downloading and installing the latest Windows Installer.

From this Microsoft support document:

This problem can occur if one of the following conditions is true:

The Windows Installer files that are on your computer are damaged or are missing.

You install or remove a program that uses the Windows Installer Microsoft Software Installation (MSI) package file (.msi). For example, this can occur when you try to install Microsoft Office on your computer.

1: Reregister the Windows Installer

verify the location of the Msiexec.exe file on your computer and in the Windows Registry, and then reregister the Windows Installer.

2: Reinstall the Windows Installer

To reinstall the Windows Installer, rename the damaged Windows Installer files, and then reinstall the Windows Installer.

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