QuickBooks Error 1618 -- Another Installation Is Already in Progress

QuickBooks Error 1618 blocks installation when another MSI-based setup is already running; our engineers explain how to clear the conflict and complete your install.

QuickBooks Error 1618 stops the Desktop installer before it can write a single file to disk. The message is abrupt, but the underlying cause is narrow: the Windows Installer service is already busy with another setup package and cannot accept a second request. Our engineers have resolved this error across every supported QuickBooks Desktop edition, and in nearly every case the fix takes only a few minutes once you know where to look.

What the Error Message Says

The full text displayed by the QuickBooks installer reads:

Error 1618: Another installation is already in progress. Complete that installation before proceeding with this one.

In some cases the QuickBooks Install Wizard may also show a secondary dialog referencing the Windows Installer service or display a generic "Installation was interrupted" message alongside the 1618 code.

What the Code Means

Error 1618 is a standard Windows Installer return code, not a QuickBooks-specific fault. When any MSI-based setup launches, the Windows Installer service places a global lock on the installation queue. That lock prevents two setup packages from writing to the same registry locations, shared component store, and file paths at the same time. Until the first installation finishes or is cancelled and its process fully exits, every subsequent MSI-based installer receives the 1618 code on launch.

What Triggers It

The most common triggers our engineers see are:

• A Windows Update running in the background, installing runtime components such as the .NET Framework, a C++ redistributable, or a cumulative OS update.
• Another application setup — Office, Adobe, a printer driver package, or a third-party tool — left running or paused at a confirmation prompt.
• A previous QuickBooks installation that crashed or was force-closed, leaving the Windows Installer service in a hung state where it believes an install is still active.
• A stuck or orphaned MSI process registered in the service's internal queue with no visible setup window on screen.

How to Fix It

Our engineers recommend working through these scenarios in order, starting with the most common cause.

1. Wait for or cancel the other installation

Check the taskbar and any secondary monitors for an active setup window. If you find one, either let it finish or cancel it cleanly through its own interface. After the other setup exits, wait roughly sixty seconds for the Windows Installer service to release its lock, then launch the QuickBooks installer again.

2. Check Task Manager for running setup processes

If no installation window is visible, open Task Manager (Ctrl + Shift + Esc) and look on the Details tab for processes named msiexec.exe. There will normally be one instance running as a system service; that is expected. If you see additional msiexec.exe entries with active CPU or memory usage, a background setup is still running. Allow it to finish, or select it and choose End Task if you are certain it belongs to a stalled or unwanted package. Then retry the QuickBooks install.

3. Restart the Windows Installer service

When a previous setup crashed, the Installer service can remain locked. To clear it:

1. Press Win + R, type services.msc, and press Enter.
2. Scroll to Windows Installer in the list.
3. Right-click it and select Restart. If Restart is greyed out, select Stop, wait ten seconds, then right-click again and select Start.
4. Close Services and relaunch the QuickBooks installer.

4. Reboot the workstation

If the service will not stop or restart, a full reboot clears the Installer queue and releases any orphaned locks. After the machine comes back up, sign in and run the QuickBooks setup before launching any other applications.

5. Clear the pending installation registry key

When none of the above resolves the error, a stale entry in the Installer's pending-action registry key may be signalling an in-progress installation that no longer exists.

1. Press Win + R, type regedit, and press Enter.
2. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\InProgress.
3. If the InProgress key contains values referencing an active setup, right-click the InProgress folder and export it as a backup.
4. Delete the contents of the InProgress key.
5. Close Registry Editor, reboot, and retry the QuickBooks installation.

How to Prevent It Recurring

Before launching any QuickBooks Desktop installation or update, close all other applications, pause background Windows Updates if a restart is pending, and verify that no other setup package is running. On managed networks, coordinate with your IT administrator so that group-policy software deployments do not overlap with the QuickBooks install window. Following those steps keeps the Windows Installer queue clear and lets the QuickBooks setup proceed without conflict.