Window Defender Error 577: Fixed


Windows Defender is free to use and comes with an operating system, so you can start defending yourself immediately. But recently, consumers have begun to notice a Windows Defender error 577. There are numerous causes and remedies that you might look into.

Windows Defender protects your Windows machine from outside attacks that could corrupt it and render it unusable. Many customers have reported receiving a Windows error 577. When this problem appears, you are unable to launch Windows Defender. There are several ways to resolve this problem, including deleting all third-party antivirus software and altering registry entries. You can also scan the system using SFC.

If you’re currently dealing with error 577 of Windows Defender, work through the different solutions mentioned ahead.

See Also: 9 Methods On How To Clear Cache In Windows 10 Using Run

What may be the root of error 577 in Windows Defender?

When using Windows Defender, you may experience the “Windows will not start on Windows 10 ” issue with error code 577.error 577

Most of the time, a PC with third-party antivirus software will see the error 577 in Windows Defender. Another potential reason is faulty Windows Defender registry key. Or the group policy could prevent the Windows Defender from running.

Fixes for Windows Defender error 577

The solutions listed below could be helpful if you are currently experiencing Windows Defender error 577. Unless you find a solution, follow the possible solutions in the order:

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Remove all third-party antivirus programs.

To avoid any clashes, Windows will stop the built-in security package (Windows Defender) when you remove a third-party antivirus program. 

If the third-party security program was a demo, your OS may still think you’re running an additional antivirus program, which could result in the Windows Defender 577 error.

Your greatest chance of launching Windows Defender without encountering error 577 on Windows 10 is to remove all traces of your secondary antivirus product if you find yourself in a position similar to this one.

Instruct your operating system to launch the integrated antivirus program automatically because of this.

Steps to follow:

  1. Launch the Run window by pressing the Windows key and R.
  2. Search “appwiz.cpl” and hit Enter to open Applications and appwiz
  3. Examine the list of installed programs and remove the item for your third-party antivirus.programs and features
  4. Once the external security program has been eliminated, reboot your computer and check to see if Windows Defender can now be launched without encountering the Windows Defender 577 problem.

Alter the Registry.

Changing the Registry is the second way to fix Windows Defender error 577. Consequently, carry out the subsequent actions to modify the registration.

Steps to follow:

  1. Hold up the Window key as well as the R button simultaneously in order time to launch the Run dialog. In the field, enter regedit, and then click OK to proceed.enter regedit
  2. Go to the specific folder using the Registry Editor window’s given path:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defenderdisable antivirus
  3. Then, after clicking twice, update the data value of the Disable Antivirus key to 1.disableantivirus
  4. Then, restart your computer for the changes to take effect, and launch Windows Defender once more to see if the Windows Defender problem 577 Windows 10 has been fixed.

Scanning with System File Checker (SFC)

Every operating system is built on various files, each of which performs a specific task. Using SFC, you ought to look for damaged Windows Defender files.

Steps to follow:

  1. By entering cmd into the search box next to the Start Menu button, Command Prompt will be opened.
  2. Right-click the Command Prompt and select Run as administrator.command prompt
  3. After launching the console, enter the sfc /scannow command.sfc scan
  4. Restart your computer when the mending process completes.

Start the Windows Defender Service again

Attempting to reboot the Windows Defender service is the next fix for Windows Defender error 577 on Windows 10.

Steps to follow:

  1. For the Run dialog, concurrently hit the Start button and R. Type services.msc into the box and select OK to msc
  2. Drop down to locate the Security Center service within the pop-up menu, then right-click it and select Restart to restart
  3. Restart your computer, launch Windows Defender, and check for the Windows error 577.

See Also: Top 6 Ways To Fix Your “Windows Defender Security Center Won’t Open” Issue

System Restore point usage

Employ a prior System Restore point to return your computer to a time when Windows Defender was functioning perfectly.

On computers that have seen significant malicious malware, this problem—a form of suspiciousness to Windows Defender—is rather typical. Some malware programs have the power to disable Windows Defender to the extent that they can no longer be started.

Steps to follow:

    1. To launch the Run box, press the Windows key + R. The system Restore wizard will then launch once you type “rstrui” and press box
    2. At the first prompt in the System Restoration window, click Next. Then, choose the box next to Display more restore points.
    3. Next, select a restore point before Windows Defender starts giving you trouble, and press the Next button again.
    4. Hit Finish once more to launch the restoration procedure. The previous state will be restored at the subsequent startup, so bear in mind that your machine will restart promptly. 

After your machine restarts, you should no longer get the Windows Defender 577 problem.


How can I remove threats blocked by Windows Defender?

Select Virus & threat protection under Start > Settings > Update & Security > Windows Security. Choose Modify settings underneath Virus & Threat Protection Settings, and under Exclusions, choose Add or eliminate exclusions.

Is Windows Defender manually updatable?

The most recent updates for Microsoft Defender are also readily available to download from the Microsoft website. The steps for downloading updates for Microsoft Security are as follows: Find the 'Manually download the update' option by scrolling down the Microsoft Security Intelligence Updates page.

Can one remove Trojan using Windows Defender?

Microsoft Defender is a free antimalware program that was first included with Windows XP and shielded Windows users from bugs, malware, and other spyware. One can use it to find and get rid of the Trojan from your Windows 10 computer.

Is Windows Defender as effective as antivirus software?

An adequate alternative for fundamental antivirus defense is Microsoft Defender. It has a good variety of options for application and security technology, as well as a highly powerful firewall. Unfortunately, the scanning performance is quite subpar, and the only software that enables safe surfing is Microsoft Edge.


Microsoft’s built-in security program, Windows Defender, protects your Windows computer from the exterior risks that may arise that could corrupt your system. The majority of the time, PCs that have used or are presently utilizing an external antivirus program will get the Windows Defender Error 577. There were various workarounds discussed to tackle the Windows defender error. There was also a section to address all the questions that were frequently asked on this topic for better understanding.

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