Windows MSI Error 1618 — Another Installation Already in Progress

MSI error 1618 occurs when you try to run an MSI installer while another Windows Installer operation is already running, as Windows allows only one at a time. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: Windows Installer (msiexec.exe) only allows one installation at a time. Error 1618 means another MSI-based installation is currently running. Background Windows Updates using MSI can lock the installer service. Silent installations from IT management tools often run unnoticed. The _MSIExecute mutex controls single-instance enforcement. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Another MSI installer is running in the background (Windows Update, SCCM). Previous installation hung and did not release the installer lock. Windows Update downloading and installing updates using MSI packages. Software deployment tool (SCCM, Intune) running a silent installation. Msiexec.exe process zombie still running from a failed install. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Wait for the current installation to finish — check Task Manager for msiexec.exe processes. Open Task Manager > Details tab > end all msiexec.exe processes, then retry. Restart the Windows Installer service: net stop msiserver && net start msiserver. Pause Windows Updates temporarily: Settings > Update & Security > Pause updates. Reboot the computer to clear all installer locks and retry. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Windows Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.