How to fix Windows Defender error 577 in Windows 10

Although there are various alternatives that outrace the in-built antivirus designed by Microsoft, Windows Defender still remains as one of the favorites around many users because it comes along Windows installation and requires no fee to start being protected right off the bat. Recently, however, people started seeing a warning that Windows Defender is disabled and does not implement any protection. Some people tried to go in Services and launch Windows Defender Antivirus Service or Network Inspection Service. After attempting to do so, users receive error 577 saying that Windows cannot verify the digital signature for the file. If this is exactly your case, we will share some other methods to solve the issue down below.

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1. Change values in registry

The first thing you can try out right away to fix error 577 is to alter some values of Windows Defender registry keys. Here are the steps:

1. Press both Windows + R at the same time and paste regedit into the opened tab. Click OK to submit.
2. Once Registry Editor opens, on the left panel navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender.
3. In the right panel find and double click on DisableAntiSpyware and DisableAntiVirus DWORD and change their values from 0 to 1.
4. Click OK to save changes.

Some users say that you can also try to change values of the same entries in this route HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender.

2. Change permissions in your Registry

Before you leave Registry, we advise you to try another option – adjust security permissions that are responsible for Windows Defender. Although, because such changes can impact your system badly, it is advised to create a backup before committing this action in case something goes wrong. To change Security Permissions, follow the steps below to:

1. Open Registry Editor likewise we did above.
2. Go to these folders HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft. Find and right-click on the Windows Defender folder and choose Permissions from the drop-down menu.
3. In the opened window, locate Advanced and click Add afterward.
4. Now click on Select a principal.
5. A new tab should appear where you have to type your user name in the Enter the object name to the selected field and click OK to save changes.
6. Now your user name will appear in the Principal section. Make sure you select “Full Control” in the “Basic permissions” section and click OK to save changes.
7. Finally, click Enable Inheritance under the Add button and click Apply button to complete the changes.

3. Install fresh Windows updates

Some Windows services like Antivirus can be bugged or no longer supported due to outdated updates. If you always forget to install fresh updates that hang in your notification center, then this might be the reason. Some people may argue that new updates can affect your system negatively, but you can always roll them back to previous versions, if necessary. This is how you can install new system updates:

1. Press Windows + I combination and choose Update & Security.
2. Then go to Windows Update and click on the Check for updates button. If your Windows found new updates automatically, just click on Install/Download and follow on-screen instructions.
3. After your PC gets rebooted, you can try to use Windows Defender once again.

4. Delete/Disable anti-malware software

If you are using third-parties software, this can conflict with Windows settings. Simply disable it through the Task Manager and try to launch Windows Defender. If this does not help, you can try to uninstall additional antivirus completely for the time being.

5. Reboot Security Center service

According to forums dedicated to error 577, restarting the above-mentioned can help you a lot. To do this:

1. Press Windows + R buttons at the same time, paste services.msc in the field, and click OK.
2. Then, locate Security Center, right-click on it, and choose the Restart option.

6. Run a System File Checker (SFC) scan

Any operating system is based on multiple files that execute its own function. In our case, you should check if Windows Defender files have been corrupted.

1. Open Command Prompt by typing cmd into the searching box next to the Start Menu button.
2. Right-click on Command Prompt and choose Run as administrator.
3. Once the console is opened, type the sfc /scannow command and click Enter.
4. When the fixing process is done, restart your computer.

7. Scan your PC for malware

This method might be the final solution if none of the previous work out. Some Windows processes can be violated due to accidentally downloaded infections. Most malware tends to disable Windows services to prevent itself from being detected or neutralized. This is why we recommend you run a thorough scan with a help of antimalware software. Our team recommends you to download the trial version of Norton Antivirus. It includes one free deletion of found threats so that you do not need to pay for the full activation.