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Apps, installers & Microsoft Store · scoped error record
Error 1618

Another Windows Installer installation is already in progress

1618 means Windows Installer reports another installation already running; finish or clear the legitimate pending operation before retrying.

Applies to: Windows Installer (MSI)Reviewed: 2026-09-17

What it means in this context

Microsoft defines Windows Installer Error 1618 (ERROR_INSTALL_ALREADY_RUNNING) as another installation already being in progress. This is a concurrency/state error, not evidence that the MSI package itself is corrupt.

Diagnostic state

What is known, and what is not proven yet

Keep observation, evidence and conclusion separate before making a higher-impact change.

Observed fact

Windows Installer returned 1618.

Windows evidence

Concurrent setup/update state and result after one restart/single-installer retry.

Likely subsystem

Windows Installer concurrency/state.

Evidence still needed

Whether a legitimate installer/update is active or the state persists when Windows is otherwise idle.

Safe next action

Finish/restart, then retry one installer only.

Handoff boundary

IT/vendor if deployment tooling or managed installs keep the installer busy.

Start here
  1. Wait for visible installers, Windows/app updates or setup processes to finish.
  2. Restart Windows once if no legitimate installation is visibly active.
  3. Retry only one installer after restart.
  4. If 1618 immediately returns, preserve installer/update context rather than ending random msiexec processes.
1

Return Windows Installer to a single-install state

Low risk

Why: 1618 specifically represents concurrent installation state.

  1. Close other setup programs.
  2. Allow pending update/install operations to finish.
  3. Restart the PC if the installer state is unclear.
  4. Run only the intended installer and record whether 1618 repeats.
Scope boundary

When not to use this record

Do not kill every msiexec process or delete installer registry state when an enterprise deployment, update or another legitimate setup may still be running.

If it persists

If 1618 persists immediately after a clean restart with only one installer launched, collect installer/event context and involve IT or the software publisher.

Evidence

Reviewed source

Related authority records

Continue with the same failing system

These links share the same component or repair context; they are not generic keyword suggestions.

GuideDesktop program will not install, update or uninstall in Windows 11

Separate a desktop installer problem from Microsoft Store/MSIX deployment, then use repair, uninstall and installer evidence in the least disruptive order.

ErrorError 1603 — Windows Installer fatal installation error

1603 is a fatal MSI installation failure, but Microsoft documents multiple possible conditions; preserve package/context before applying a fix.

ErrorError 1619 — Windows Installer package could not be opened

1619 means the MSI package could not be opened; verify the file exists, is accessible and is a valid publisher-supplied Windows Installer package.

ErrorError 1620 — Windows Installer package is invalid or cannot be opened as a valid package

1620 is a package-validity/opening error; verify the installer with the publisher instead of applying generic Windows repairs.

GuideMSI installer failed in Windows 11: create one verbose Windows Installer log before guessing

Use the exact MSI code first; when the cause is still unclear, a controlled /L*V log can preserve the Windows Installer sequence for support.

Commandmsiexec — install MSI with verbose log

Run one MSI installation attempt while writing a verbose Windows Installer log that can be correlated with the exact failure code and provided to the software publisher or IT.