How to Fix “Another installation is in progress” Error on Windows

Our users reported that they could no longer install applications. Whenever they tried to install applications, they received the following message: “Another installation is in progress. You must complete that installation before continuing this one.”

The problem was due to a registry key-HKLM\SOFTWARE\Microsoft\CurrentVersion\Installer\InProgress.

As the name implies, the key is created when an installation is in progress. The key should be deleted automatically after the installation is done. In this case, the installation was never finished and the key was left in the registry. I tried to delete the registry key and rebooted the machine. It did not fix the problem. The registry key was created again after I rebooted the machine. I later found that the registry key was created by a program called ScreenConnect. I had to uninstall the program, but because of the registry key blocking installation and uninstallation, I could not uninstall ScreenConnect.

To solve this dilemma, I discovered that I needed to boot the machine to safe mode with networking, enable Windows installer service under safe mode with networking. Only then could I uninstall the program and fix the problem.

Here are the steps:

1. Boot the computer to safe mode with networking. On a Windows 7 machine, you can do this by pressing F8 before the OS loads.
2. Open an elevated command prompt.
3. Type the following two commands in the command prompt. Note that the first command might be wrapped to the second line. Make sure you get it right.

   reg add "HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Network\MSIServer" /VE /T REG_SZ /F /D "Service"
   net start msiserver

4. Install a program. This could be any program using Windows installer. You will be prompted to cancel the previous pending installation. This is fine, so just follow the prompts to remove the pending installation.
5. If you know which program caused the initial problem, you need to uninstall the program. In this case, our problem was caused by ScreenConnect, so I uninstalled it.

After you reboot the computer normally, you should be able to install applications without getting the “Another Installation is in Progress” error.