Windows Modules Installer: Check & Start Service

This guide shows you how to check the status of the Windows Modules Installer service and start it when it’s stopped or disabled. This service handles Windows Update installations and some driver or software setups, so getting it running again is often the fix for update errors that stall at “Downloading” or “Installing” with no progress.

What You’ll Need

An account with administrator privileges on the Windows PC
Windows 10 or Windows 11 (steps are nearly identical on both)

Step-by-Step

Open the Services console. Press Win + R to open the Run dialog, type services.msc, and press Enter. If a User Account Control prompt appears, click Yes.
Find the service. In the Services window, scroll down the list (it’s alphabetical) until you see Windows Modules Installer. Its short name is TrustedInstaller.
Check its status. Look at the Status column. If it says Running, the service is active. If the column is blank, it’s stopped. Also check the Startup Type column — it should be Manual (default) or Automatic.
Start the service. Right-click Windows Modules Installer and choose Start from the context menu. Wait a few seconds; the Status column should change to Running.
If Start is greyed out, the service is disabled. Right-click it, choose Properties, and in the Startup type drop-down, select Manual. Click Apply, then click the Start button in the same window. Click OK.
Verify it’s running. Double-check the Status column now shows Running. Close the Services window.
Retry your update or install. Go back to Windows Update (or the program that was failing) and try again. The service will stop itself when the work is done — that’s normal.

Common Mistakes

Forgetting to run as administrator: If you open Services without admin rights, the Start option may be greyed out or you’ll get an “Access Denied” error. Always confirm the UAC prompt.
Setting startup type to Automatic: The Windows Modules Installer is designed to run on demand. Forcing it to Automatic can cause it to start at boot and stay in memory, which isn’t harmful but is unnecessary and can slow startup slightly.
Stopping the service manually: If you stop TrustedInstaller while an update is mid-install, you can corrupt the update. Only stop it if you’re troubleshooting and know what you’re doing.
Confusing it with Windows Update service: The Windows Modules Installer is separate from Windows Update (wuauserv). If the Modules service is running but updates still fail, check that the Windows Update service is also running.

Tips

Use the command line for speed: Instead of the GUI, open Command Prompt as administrator and type net start TrustedInstaller. You’ll see “The requested service has already been started” if it’s running, or “The service is starting” if it starts successfully.
Check dependencies: The Windows Modules Installer depends on the Remote Procedure Call (RPC) service. If starting it fails, make sure RPC is running (it usually is, as it’s critical for Windows).
Restart after major updates: If you’ve just installed a large Windows feature update, the Modules service may be busy in the background. Give it 10-15 minutes before checking its status.
Use the Windows Update troubleshooter: If the service keeps stopping on its own, run the built-in troubleshooter: Settings → System → Troubleshoot → Other troubleshooters → Windows Update → Run.

Troubleshooting

When you click Start, nothing happens or it immediately stops. This usually means the service is crashing. Check the Windows Event Log: open Event Viewer (eventvwr.msc), go to Windows Logs → System, and look for errors from source “Service Control Manager” or “TrustedInstaller” around the time you tried to start it. The error code will point to the cause — common ones include corrupted update files or a full system drive.

If the service is disabled and you can’t change it. Some third-party “debloat” scripts disable this service. To re-enable it, open an elevated Command Prompt and run: sc config TrustedInstaller start= demand. Then try starting it with net start TrustedInstaller. If that fails, you may need to repair Windows with the DISM tool: DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow.

If the service starts but Windows Update still fails. The problem isn’t the service itself. Clear the SoftwareDistribution folder (stop Windows Update service first, delete contents of C:\Windows\SoftwareDistribution, restart the service) and try again. If that doesn’t help, the update files may be corrupted — use the Windows Update troubleshooter or the Media Creation Tool to do an in-place repair upgrade.

If you see error 0x80070005 (Access Denied) when starting. This indicates a permissions problem. Make sure your user account is in the Administrators group. If it is, try taking ownership of the service registry key: in Regedit, navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TrustedInstaller, right-click, Permissions, and grant Full Control to Administrators. Then start the service again.

Frequently Asked Questions

Is it safe to disable Windows Modules Installer?

No. Disabling it will break Windows Update and many Microsoft Store app installs. It only runs when needed, so there’s no benefit to disabling it.

Why does the service stop by itself after I start it?

That’s normal. It starts when an update or installation requests it, does the work, and stops when finished. If it stops immediately without doing anything, check the Event Log for errors.

What is TrustedInstaller?

TrustedInstaller is the internal name of the Windows Modules Installer service. You’ll see it in Task Manager and in file permissions — system files are often owned by “TrustedInstaller” to prevent tampering.

Can I manually run Windows Modules Installer to force an update?

No, the service itself doesn’t have a user interface. It’s called by Windows Update and other installers. Starting the service manually just makes it available; it won’t trigger any update on its own.

Will starting this service fix all Windows Update errors?

No. It fixes errors specifically caused by the service being stopped or disabled. Many update errors come from other causes like corrupted update cache, network issues, or disk space problems.

How do I know if the service is running without opening Services?

Open Task Manager (Ctrl+Shift+Esc), go to the Services tab, and look for TrustedInstaller. The Status column shows Running or Stopped. You can also use the command sc query TrustedInstaller in Command Prompt.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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