Windows MSI Error 1618 — Another Installation Already in Progress

Overview

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.

Key Details

• 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

Common Causes

• 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

Steps

1. 1Wait for the current installation to finish — check Task Manager for msiexec.exe processes
2. 2Open Task Manager > Details tab > end all msiexec.exe processes, then retry
3. 3Restart the Windows Installer service: net stop msiserver && net start msiserver
4. 4Pause Windows Updates temporarily: Settings > Update & Security > Pause updates
5. 5Reboot the computer to clear all installer locks and retry

Tags

More in Installer

Frequently Asked Questions