The blog of Windows Wally, a Windows Support Technician helping common people solve frustrating computer problems.

How To Fix The “The Windows Installer Service Could Not Be Accessed” Error

Reader Question:
“Hi Wally, I see this error whenever I try to install something on my computer. “The Windows Installer Service Could Not Be Accessed”. It is a Windows 7 laptop. Thank you.“ - Ms Olfa

Before addressing any computer issue, I always recommend scanning and repairing any underlying problems affecting your PC health and performance:

  • Step 1 : Download PC Repair & Optimizer Tool (WinThruster for Win 10, 8, 7, Vista, XP and 2000 – Microsoft Gold Certified).
  • Step 2 : Click “Start Scan” to find Windows registry issues that could be causing PC problems.
  • Step 3 : Click “Repair All” to fix all issues.

Setting up weekly (or daily) automatic scans will help prevent system problems and keep your PC running fast and trouble-free.

Wally’s Answer: Windows 7 is a pretty solid operating system however others like this do occur.

Errors that prevent you from installing a program on Windows 10 are pretty rare. But don’t worry. We should be able to fix this problem easily.

Simply follow the troubleshooting steps as shown and you should be able to use Windows normally again.


When the user tries to install a program on Windows 7 (or Windows Vista) they see the following error message.

The Windows Installer service could not be accessed. This can occur if the Windows Installer is not correctly installed.

Windows Installer -- Cover - Error - Windows Wally


Here are two methods to solve this problem. If the first method does not work then please try using the second method.

Reset the Windows Installer Service

Here, we will be resetting the Windows Installer Service from its registry entry.

Note: This step requires that you modify the registry. The registry is at the heart of the Windows operating system. Please read this article for happy and safe registry editing.

All you need to do is to make a Notepad file and run it. It is really that simple.

Please open NotePad and copy the following text in it (this is from a Microsoft support article):

Windows Registry Editor Version 5.00



Save the file as Msirepair.reg and make sure the type of file is set to All Files (*.*) as shown here

Windows Installer -- Notepad - Msirepair.reg - Windows Wally

Run this file to reset the Windows Installer Service from the registry.

Start The Windows Installer Service

Press the Windows Key and type command prompt. Right-click Command Prompt and click Run as Administrator to start it.

Windows Installer -- Windows 10 - Start Menu - Command Prompt - Run as Administrator - Windows Wally

Type net start MSIServer on your keyboard and press ENTER

Windows Installer -- Windows 10 - net start MSIServer - Windows Wally

Now, try to install that program again. Uninstall the program before installing it again.

Checking If the Windows Installer Service is Running

You can check to see if the Windows Installer service is running right now. You can do this by following these steps:

Press Windows Key+R to open the RUN dialog box.

Type services.msc and press Enter

Windows Installer -- Windows 10 - services.msc - Windows Wally

You should see something like this

Windows Installer -- Windows 10 - services.msc - 2 - Windows Wally

Now, look for the Windows Installer service in the list.

Once you find it, Double click it to see the properties.

Make sure that the Startup type is set to Manual

Windows Installer -- Windows 10 - services.msc - 4 - Windows Wally

If the service status is Stopped and click Start to start the service. It is supposed to turn on when needed, but maybe it was not triggered to start for some reason.

I Hope You Liked This Blog Article! If You Need Additional Support on This Issue Then Please Don’t Hesitate To Contact Me On Facebook.

Is Your PC Healthy?

I always recommend to my readers to regularly use a trusted registry cleaner and optimizer such as WinThruster or CCleaner. Many problems that you encounter can be attributed to a corrupt and bloated registry.

Happy Computing! :)

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About the Author

Windows Wally is a helpful guy. It’s just in his nature. It’s why he started a blog in the first place. He heard over and over how hard it was to find simple, plain-English solutions to Windows troubleshooting problems on the Internet. Enter: Windows Wally. Ask away, and he will answer.