1618

What it means

Windows Installer serialises installs with a mutex called _MSIExecute. If a second install starts while the first still holds it, the second one exits with 1618 immediately. It is not a failure of your package, it is a collision.

Real causes

• Windows Update or a scheduled maintenance task started an install at the same time as your deployment.
• A previous msiexec process is hung and never released the mutex.
• Two deployments were targeted at the same device in the same window.

What to do

1. Retry. Most deployment tools will succeed on the next attempt without any change.
2. Check for a stuck installer: Get-Process msiexec | Select-Object Id, StartTime
3. Stagger deployments so they do not land in the same maintenance window as patching.
4. Build a retry with a short delay into the install command rather than marking the device failed on the first attempt.

Where to look

• Application event log, MsiInstaller source

Checked against Microsoft documentation. Last reviewed 2026-08-20.

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