Only one instance of Wusa.exe is allowed to run [Fix]

by Madalina Dinita

Former Managing Editor

April 23, 2019

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Let’s say you’re trying to get the latest update for your Windows, and you’re greeted by the following error Only one instance of wusa.exe is allowed to run. What now? This error mostly occurs when you’re trying to install a Windows Standalone Update package, while the Windows Update is still running in the background.

Let’s take a closer look at the following solutions, and see if they help you out.

How to fix Only one instance of Wusa.exe is allowed to run error?

1. Windows Installer check-up
2. View your event log
3. Run Task Manager
4. Re-register Windows Installer
5. Reinstall Windows Installer in Safe Mode

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1. Windows Installer check-up

If you’re getting Only one instance of wusa.exe is allowed to run error, you need to check if  Windows Installer service is running or not.

1. Click Start, type services.msc and press Enter.
2. Double-click Windows Installer.
   
3. Set the Startup type of your Windows Installer to Manual.
   
   
4. Click Start to start the service.
5. Click OK.

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2. View your Event Log

If you’re getting Only one instance of wusa.exe is allowed to run error, you might be able to find the cause by visiting the Event Log. To do that, follow these steps:

1. Select your Search box, and then click Event Viewer in the Programs list.
2. In Event Viewer, expand your Windows Logs, and then click Setup.
3. In the Actions sections, click Filter Current Log.
   
4. In the Event sources list, click to select the wusa check box, and then click OK.
5. Now you can switch between instances of wusa and identify the cause of the problem.

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3.Run Task Manager

You can also fix Only one instance of wusa.exe is allowed to run error by using Task Manager. Follow these steps:

1. Start Task Manager.
   
2. Go to start task.
3. Start wusa.exe.
4. When wusa.exe is running, go into the Task Manager, simply end the process tree for any process under the name wusa.exe.
5. Close the Task Manager.

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4. Re-register Windows Installer

Another way to fix Only one instance of wusa.exe is allowed to run error is to re-register Windows Installer. To do that, follow these steps:

1. Click Start, and type %windir%system32msiexec /unregserver in the Start Search box, and then press Enter.
2. Type %windir%system32msiexec /regserver , and then press Enter.
3. If you are prompted for an administrator password or for a confirmation, type your password.

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5. Reinstall Windows Installer in Safe Mode

Just boot your machine into Safe Mode, from the Advanced startup options. And now try to run the update. Remember that wusa.exe enables the appropriate function in the Windows Update Agent according to the mode in which you start wusa.exe.

Tip

In the event that this issue persists,  you may want to reset the Windows Update Components and see if that solves the issue. When running an update, make sure to momentarily disable any anti-virus software running in the background, for it may be interfering with your connection.

We hope that these fixes were able to help you fix the Only one instance of wusa.exe is allowed to run error. In the meantime, let us know what other types of errors have you stumbled upon recently.

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