You may start defending yourself immediately because Windows Defender is free to use and comes with an operating system. For quite a while, consumers have started to see Windows Defender error 577 recently. There are several causes and solutions you could research.

Your Windows computer is shielded from external threats that could corrupt it and render it unusable by Windows Defender. There have been numerous reports of Windows error 577. Windows Defender cannot be started when this issue arises. This issue can be fixed in several ways, including removing all third-party antivirus programs, Changing your registry, Turning on Windows Defender from Notification Center, Changing the security permissions in your Registry, and editing registry entries. SFC is of use to scan the system as well.

Work through the options listed above if Windows Defender error 577 is a problem you’re now experiencing.

See Also: 5 Ways To Fix Windows Defender Blocked By Group Policy

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

While using Windows Defender, you may encounter the “Windows will not start on Windows 10 ” problem with error code 577.

A computer running a third-party antivirus program will frequently experience Windows Defender error 577. A Windows Defender registry key that has been corrupted is another probable reason. error 577 in windows defenderAlternatively, group policy could stop Windows Defender from launching.

Fixes for Windows Defender error 577

You might find the solutions below useful if you are currently dealing with Windows Defender error 577. Follow the alternative approaches in the order until you find one.

Remove all third-party antivirus programs.

When you uninstall a third-party antivirus product, Windows will disable its protection suite (Windows Defender) to prevent conflicts.

Your OS can still believe you’re running an additional antivirus application if the third-party security program was a demo, which could cause the error 577 on Windows 10. Check this out if you want to disable antivirus.

If you find yourself in a similar situation, removing all traces of your secondary antivirus program will give you the best chance of launching Windows Defender on Windows 10 without running into error 577.

Instruction to 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. Search “appwiz.cpl” and hit Enter to open Applications and appwiz
  2. Examine the list of installed programs and remove the item for your third-party antivirus.programs and featuresOnce the external security program has been eliminated, reboot your computer and check to see if Windows Defender can 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 and 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 Defender. Then, after clicking twice, update the data value of the Disable Antivirus key to 1.disable antivirusThen, restart your computer for the changes to take effect, and relaunch Windows Defender to see if you have fixed the Windows Defender problem 577 Windows 10.

Scanning with System File Checker (SFC)

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

Steps to follow:

  1. Command Prompt will open by entering cmd into the search box following the Start Menu button. Run as administrator can be selected by right-clicking the Command Prompt.command prompt
  2. After launching the console, enter the sfc /scannow command.sfc scan 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 Restart your computer, launch Windows Defender, and check for 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 last System Restore point to return your computer to a time when Windows Defender was functioning perfectly.

This problem—a form of suspiciousness to Windows Defender—is typical on computers that have seen significant malicious malware. Some malware programs have the power to disable Windows Defender to the extent that they can no longer start.

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.restore point
    3. Next, select a restore point before Windows Defender starts giving you trouble, and press the Next button again.system restore point Hit Finish once more to launch the restoration procedure. The previous state restores at the subsequent startup, so remember that your machine will restart promptly. 

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

See Also: Fix: Windows Defender Has Been Turned Off By Group Policy


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 application and security technology options, 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. Most of the time, PCs that have used or are 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 frequently asked questions on this topic for better understanding.

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