We all have all sorts of applications that we use on daily basis installed on our Windows 10 PCs. Unfortunately, few users reported “Windows Installer Service could not be accessed“ error while trying to install new applications. This sounds rather serious, but there’s a way to fix this error.
“Windows Installer Service could not be accessed“ on Windows 10
Solution 1 – Reset Windows Installer Service registry
In order to perform this step you need to add certain values to the registry. Bear in mind that modifying registry can cause system instability if not performed properly, so make sure you create a backup. To create a backup of your registry, do the following:
- Press Windows Key + R and enter regedit. Press Enter or click OK.
- Once Registry Editor opens, select File > Export.
- Select All as Export range, enter the name of the file and click Save. In case anything goes wrong, you can just run this file and restore your registry.
- Once you’ve created your backup, close Registry Editor.
- READ ALSO: How to Clean Install Windows 10 on a SSD
With registry backup created, you need to create a .reg file and add it to registry. To do that, follow these steps:
- Open Notepad.
- Paste the following text into Notepad:
- Windows Registry Editor Version 5.00
- Windows Registry Editor Version 5.00
- Click File > Save as. As the name of file enter repair.reg and set Save as type to All Files and click Save.
- Close Notepad.
- Locate the repair.reg file, right click it and choose Run as administrator.
- If prompted, click Yes.
After you’ve added repair.reg to the registry, try to install the problematic application again.
Solution 2 – Start the Windows Installer Service manually
If you’re having “Windows Installer Service could not be accessed“ error, you might want to try starting the Windows Installer Service manually. To do that, you need to follow these steps:
- Press Windows Key + X and choose Command Prompt (Admin) from the menu.
- Once Command Prompt opens, enter net start MSIServer and press Enter to run it.
In order to check if the Windows Installer Service is running, you need to do the following:
- Press Windows Key + S and enter Services. Select Services from the list of results.
- When Services window opens, locate Windows Installer service and double click it.
- Check the Service Status in order to see if the Windows Installer service is running.
- If the service isn’t running, click the Start button to start it.
Solution 3 – Uninstall the older version of the program you wish to install
If you already have the older version of the program you want to install on your computer, we advise you to remove that version from your PC before trying to install the newer version.
Solution 4 – Re-register Microsoft Installer Service
Sometimes you can fix “Windows Installer Service could not be accessed“ error by re-registering the Microsoft Installer Service. To do that, follow these steps:
- Press Windows Key + X and select Command Prompt from the menu.
- If you own 64-bit version of Windows enter the following lines and press Enter after each line:
- %windir%\system32\msiexec.exe /unregister
- %windir%\system32\msiexec.exe /regserver
- %windir%\syswow64\msiexec.exe /unregister
- %windir%\syswow64\msiexec.exe /regserver
After you’ve entered all the lines, close Command Prompt and restart your computer.
If you own 32-bit version of Windows 10, you need to enter the following commands:
- msiexec /unregister
- msiexec /regserver
After you’ve entered them, close Command Prompt and restart your computer.
Solution 5 – Use regsvr32 command
In order to use this command, you’ll need to start Command Prompt as administrator. We explained how to do that in several solutions above, so make sure you check it out. Once the Command Prompt starts, enter regsvr32 c:\windows\system32\msi and press Enter to run it. Once you’ve ran the command, close the Command Prompt and try to install the problematic application again.
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“Windows Installer Service could not be accessed“ error message can create a lot of problems, but we hope that some of our solutions were helpful to you.