[Solved] Windows Defender Error 577

Sometimes, Windows Defender might not work properly and becomes unusable due to the Windows Defender error 577.

When any third-party antivirus software often interferes with the Windows Defender, you might receive this error code.

In case you frequently encounter the same error code, then apply the methods described underneath in order to resolve the error code.

Why Windows Defender Service Error 577 Appears?

The Windows Defender service error 577 comes up along with an error message stating that,

“Windows could not start Windows Defender. Error 577: Windows cannot verify the digital signature for this file. A recent hardware or software change might have installed a filed that was signed incorrectly or damaged, or that might be malicious software from an unknown source.”

This error message appears due to a number of reasons. According to the users, damaged or corrupted system files or incomplete installation of the Windows might lead you in this situation.

Apart from that, the .dll registration problem is a common reason for this annoying error. No matter whatever may be the reasons, you need to resolve the problem without wasting much  time. Hence, follow the rest of this post and apply these troubleshooting methods to get rid of this situation.

How To Eliminate Windows Defender Error 577 in Windows 10?

If you are currently struggling with the Windows Defender error 577 in Windows 10, then the solutions stated below will most likely help you to resolve the issue.

Fix 1: Uninstall Third-Party Antivirus Software, if any

In case, if you have installed any third-party antivirus software on your device, then you need to uninstall it from your device. A certain number of people reported third-party antivirus software interferes with the Windows Defender and due to this, the error code appears on the system screen.

To uninstall the antivirus software from your device, follow the steps mentioned in the section below.

  1. First of all, press the Start button and then move to the Control Panel section. After that go to the Programs and Features section.
  2. Here, you will find all the installed applications on your device. Locate the antivirus from the list and right-click on it.
  3. After that, select the Uninstall option from the drop-down menu. Click OK to confirm the action.

It will then take some time to complete the process. When the uninstallation process gets over, restart the system and check whether you are encountering the same error code or not.

Fix 2: Edit the Registry key

If the above method is unable to resolve the problem, then you need to edit the registry keys which are associated with the Windows Defender.

Users are managed to launch the Windows Defender on their device simply by changing the value of the DisableAntiSpyware key. To do so, follow the steps that are mentioned in the section below.

  1. First of all, press the Windows key along with the R key to launch the Run box. Now, type ‘regedit’ in the Run window and press Ctrl + Shift + Enter to launch the Registry Editor with admin permission.
  2. After that, navigate to the HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows Defender folder which is available to the left-hand side panel of the Registry Editor section.
  3. Then, choose the DisableAntiSpyware and change the value from 0 to 1. Change the value of the Disable Antivirus section from 0 to 1.
  4. After changing the values, move to the  C:\ Program Files \ Windows Defender folder. After that, select the MSASCui.exe to open the Windows Defender.

Hopefully, after performing these steps the Windows Defender tool will open up without showing any error code. Otherwise, move to the next section.

Fix 3: Using a System Restore Point

In case you are still getting the Windows Defender error code 577, then use a previous system restore point in order to revert your device.

In this state, the Windows Defender will work properly. Hence, to avoid the error code use system restore and follow the guide to perform so.

#1. At first, launch the Run window by pressing the Windows key and R key at the same time. Now, type ‘rstrui’ in the Run box and hit the Enter button.

#2. Due to this, you will move to the System Restore wizard section. Now, hit the Next button under the System Restore section.

#3. After that, check the box which is associated with the ‘Show more restore points’. Thereafter, pick the restore point from the list which is dated before you experienced the error code.

#4. Now, press the Next button. At last, hit the Finish button to open up the restoring point. Now, restart the system and check the status of the error code.

Fix 4: Run an SFC Scan

According to the users, the error code might appear due to the corrupted system files. Hence, you need to check the system files and delete them from your device.

To do that, you can scan your device with the System File Checker tool. Follow the steps mentioned in the section below.

  1. At first, open the Run dialog box and then type ‘cmd’ in the Run window. Now, right-click on the cmd icon. Now, choose Run as an Administrator from the drop-down menu in order to open the Command Prompt as an admin.
  2. After that, type ‘sfc/scannow’ in the Command window and hit the Enter key to launch the System File Checker tool on your device.
  3. It will automatically start to scan your device and locate the damaged system files.

When the process gets completed, restart the system and check if the error code 577 appears or not.

Undoubtedly, you have resolved the Windows Defender error 577 after applying the above steps. It is advisable that you do not jump any steps otherwise you need to perform the method from the beginning.