Windows Installer Service Could Not Be Accessed – In this post you will see different ways to fix the error “The Windows Installer Service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance”. The Microsoft Windows Installer is the application installation and configuration service for Windows. The Windows Installer is used for the installation, maintenance, and removal of software on Microsoft Windows systems. You may get this error when you try to install a program in Windows 7 or Windows Vista & this problem may occur if the Windows Installer files are damaged or missing.
1 Method 1: Check the Windows Installer service
1. Click Start, type Services.msc and press ENTER.
2. Double-click Windows Installer service.
3. Set the Startup type of Windows Installer to Manual.
4. Right click on the service and click Start to start the service. Note down the error message if any.
5. Click OK.
2 Method 2: Unregister and Re-register the Windows Installer
1. Click Start, click Run, type CMD and hit Enter. In the command prompt type MSIEXEC /UNREGISTER, and press Enter key. Even if you do this correctly, you may not see anything on the command prompt.
2. Click Start, click Run, type CMD and hit Enter. In the command prompt type MSIEXEC /REGISTER, and then click OK. Even if you do this correctly, you may not see anything on the command prompt.
3. Now try installing your Windows Installer-based application again.
3 Method 3: Perform SFC scan on the computer.
1.Click Start, click Run, type CMD, run it as administrator.
2. Type the following command, and then press ENTER: sfc /scannow
Note – The sfc /scannow command scans all protected system files and replaces incorrect versions with correct Microsoft versions.
3. If any files rare corrupt then SFC will replace them. You may be asked to insert your Win7 DVD for this process to continue.
4. After the scan has completed, close the command prompt window, restart the computer and check.
4 Method 4 : Registry Fix
The registry under “HKEY_lOCAL_MACHINE/SYSTEM/CurrentControlSet/services/msiserver” would have been corrupted. The solution is deleting this registry key and importing the msiserver registry key from another working machine. Restart computer then issue should be gone.
There might some more ways to fix this issue, if you know them please add to the comments. I will add them to the post.