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Windows Defender is a popular anti-malware component that protects your system against malware infections. Over time, users often raise certain issues. Many users have frequently encountered Windows Defender Error 577 with Windows Defender. At this point, you may receive an error message: “Windows can not verify the digital signature of your file.” Therefore, if you have trouble solving it yourself, we recommend that you follow the steps below and get rid of it immediately.

How to Fix Windows Defender error 577 ?

 Solution 1: Uninstall third-party anti-malware

This concerns antivirus programs mostly, but other security software, like some anti-spyware, have been reported to cause Windows Defender error 577, too.

1. Press Windows key + X
2. Select Control Panel => Programs => Programs and Features.
3. Look for the AV, highlight it and click Uninstall.
4. Reboot and try to launch Win Defender.

If error 577 has not been eliminated, the antivirus has probably not been completely removed. Find and delete any remaining files, folders, registry settings associated with it, or use an application removal tool. Revo Uninstaller is one of these tools, and you can find more in a Microsoft community.

Solution 2: Launch Defender via Services

1. Click Start.
2. Type ms and press Enter.
3. Locate Windows Defender Service in the table, right-click on it and click Start.

Solution 3: Run System File Checker to restore corrupted system files

1. Press Windows key + X
2. Click Command Prompt (Admin).
3. Type sfc /scannow and hit Enter.
4. Wait until the process completes.
   If some bad files have been detected but could not be restored, type dism / Online / Cleanup-Image / RestoreHealth and press Enter (this step requires an active Internet connection to access Microsoft servers). Wait until the end of the procedure and repeat step 3.
5. Exit Command prompt, reboot the PC.

Solution 4: Change the security permissions in your Registry

Windows Error 577 may be caused by security permissions issues. To resolve the problem, you can change the security permissions of specific keys in the registry. To do this, follow the steps below.

1. Open Registry Editor.
2. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender
3. Right click on the key and select Permissions
4. Choose the Advanced
5. Click on the Add
6. Choose Select a principal.
7. In the Enter the object name to select field type in user name and click Check Names.
8. Select OK to save changes.
9. You can see your username in the Principal  In Basic permissions section tick the box on Full Control and click OK to save changes. 
10. Choose Enable Inheritance
11. Click Apply and OK.

Solution 5: Restart Security Center and Windows Defender service

In some cases, the Windows Defender 577 error can be resolved by restarting Security Center. To restart Security Center, follow the instructions.

1. Press Windows + R.
2. Type msc, then press Enter.
3. Search for Security Center
4. Right click on it and select Restart.