Solved: The Windows Installer Service Could Not Be Accessed

Symptoms

"I recently upgraded to Windows 10 from Windows 8. Now, every time I try to download a new program, it keeps telling me the Windows Installer Service could not be accessed. The same thing happens when I try to uninstall a program. I have no clue how to fix this, and it is really hindering me. I can't install anything! Please help me. Thanks!"

Windows Installer is a Microsoft Windows component that is used for software installation, maintenance, and removal. Thus, you may receive the prompt saying "The Windows Installer Service could not be accessed' when you try to install or uninstall a program. If you see this notification, you won't be able to continue to installation or uninstallation process. Instead, you need to fix it or you will encounter the very same issue the next time you install/uninstall an application. 

Causes

As shown in the window, "Windows Installer Service could be not accessed" may occur when the Windows Installer is not correctly installed. It's no difference when the Windows Installer files are damaged or missing. Besides, the error can also be related to the Registry permissions.

How to Fix the Windows Installer Service Could Not Be Accessed Error 

Considering the causes, there are four methods available to fix Windows installer service error:

Method 1. Uninstall the Earlier Version of the Software You Want to Install

If the Windows installer is not working, you can remove the earlier version of the software you want to install before you install the new one. Installing software without removing the older version can sometimes cause unexpected issues.

Method 2. Confirm the Installer Service Is Running

To check whether the Installer Service is running, you need the Msconfig tool. The steps below are performed on Windows 10 computer.

Step 1. Go to the Windows "Start" menu, search for "Run", and click it.

Step 2. In the Open box, type msconfig, and then click "OK". 

Step 3. On the "Services" tab, click to select the checkbox that is next to "Windows Installer".

Step 4. Click "OK" > "Apply", and then click "Restart" to restart the computer. 

Method 3. Re-Register Microsoft Installer Service

If you find the Windows installer service isn't running, you can re-register the installer service. Re-registering Microsoft Installer Service is another good method to solve the Windows Installer Service could not be accessed error.

Step 1. Press "Windows + R" keys. Type cmd and hit "Enter".

Step 2. In Command Prompt, type the following lines. You need to hit "Enter" every time after each line.

If you are using 32-bit Windows, enter the commands below one by one instead.

Step 3. Close Command Prompt by entering "exit" and then restart your computer.

Now you have re-registered the Windows Installer Service. Check and see if you fix the Service could not be accessed error.

Method 4. Reinstall Windows Installer

If all the methods above all fail to help you, the last choice is to reinstall the Windows installer. 

Step 1. Press "Windows + R" keys. Type cmd and hit "Enter".

Step 2. At the Command Prompt, type the following lines and press "Enter" after you type each line.

Step 3. At the command prompt, type exit, and then press "Enter".

Step 4. Restart your computer.

Step 5. Update the Windows Installer files to the latest version. To do so, visit the Microsoft Web sites, and then download and install Windows Installer.

Step 6. After the installation of the Windows Installer is complete, shut down and restart your computer normally before you install programs.

Extra Tip: Recover Data After You Have Fixed the Error

Any of the methods above may cause data loss. If you have data loss problem after you have fixed the Windows installer service error, we can help. Reliable hard drive recovery software - EaseUS Data Recovery Wizard can help fix this problem. It’s fully compatible with Windows 10/8.1/8/7 and former Windows versions. You can free download it and follow the steps to restore lost data from Windows 10/8/7 now.