You may see an error message popping up, telling you The Windows Installer Service could not be accessed, when you try to install a software. At this time you cannot continue your installation. Here are methods that can help you get rid of this error.
It is recommended that you remove the earlier version of the software you want to install before you install the new one. Installing a software without removing the older version can sometimes cause unexpected issues.
Starting Microsoft Installer Service manually can be a good fix when you are trying to deal with the Windows Installer Service could not be accessed error.
a) Press Win + R keys. Type “services.msc” and press Enter.
b) On the Services window, scroll down to find Windows Installer.
c) Double click on that service. On the window popping up, click on Start button under Service status. (If you find the service status is Running, this service has already been started.)
d) You have started Windows Installer Service manually. Check and see if this fix the problem.
Re-registering Microsoft Installer Service is another good method to solve the Windows Installer Service could not be accessed error.
a) Press Win + R keys. Type “cmd” and hit Enter.
b) In Command Prompt, type the following lines. You need to hit Enter every time after each line.
%windir%\system32\msiexec.exe /unregister %windir%\system32\msiexec.exe /regserver %windir%\syswow64\msiexec.exe /unregister %windir%\syswow64\msiexec.exe /regserver
c) Close Command Prompt and restart your computer.
d) You have re-registered Windows Installer Service. Check and see if you fix the Service could not be accessed error.
Sometimes you can solve the Windows Installer Service could not be accessed error by resetting Microsoft Installer Service registry. To do this, follow the steps below.
WARNING: Performing this method will modify your registry and results in unexpected consequences. It is strongly recommended that you back up your registry before you proceed.
a) Open search box next to (or inside) Start Menu and search “notepad“. Open Notepad in the result.
b) Copy and paste the following codes to the notepad document file you have just opened.
Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msiserver]
c) Click on File, and then select Save as.
d) Select a place to save this file, give this file a name and put a .reg behind it. (In this case we put it on desktop and name it msirepair.reg.) Select All Files (*.*) for the saving type. Then hit Save.
e) Go to where you have saved your file, right click on the file and select Run as Administrator. Confirm your action when you are prompted to do so.
f) After you reset the registry of Microsoft Installer Service, try to install the file you want and see if the problem is fixed.