When a hardware or software is installed and does not come with a digitally signed file, it raises a suspicion of any Antivirus and Windows itself. Windows Security, aka Windows Defender, has been known to throw Error 577 when it cannot verify the digital signature in such a situation. This post will help you resolve the problem.
Windows could not start Windows Defender Service
The full error message is as follows:
Windows could not start Windows Defender Service.
Error 577: Windows cannot verify the digital signature for this file. A recent hardware or software change might have installed a file that was signed incorrectly or damaged, or that might be malicious software from an unknown source.
Windows Defender Error 577, Cannot verify the digital signature
The error usually occurs when you turn on Windows Defender, and that’s when the conflict happens with existing software. It’s not just any software, but security software that may be causing the problem.
1] Check for Residual Software
If you had installed a new Antivirus or recently uninstalled a software, then it is possible that it has left some files behind, and the uninstallation is incomplete. You will have to manually look around for files or locate an uninstaller for the program to delete it. If it is security software, then use these AntiVirus Removal Tools. If it is not on the list, you can try a free uninstaller software to delete residual files.
2] Check Webroot uninstallation
If you have used Webroot, it may not have uninstalled fully and properly. Use this tool from Webroot to complete the uninstallation and see if it helps.
3] Turn on Windows Defender
We have an exhaustive post on different ways you can follow when you cannot turn on Windows Defender. If you are comfortable with Registry, then follow these steps to turn on Windows Defender.
Press Win key + R to open Run prompt.
Type “regedit” and press the Enter key
Navigate to these keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender
Change value of ‘DisableAntiSpyware‘ and ‘DisableAntiVirus‘ from ‘0’ to ‘1‘.
If it is not there, you can create the DWORD with the same names and change the value.
Try re-running the Windows Defender, and it should work.
I hope the post was easy to follow, and you were able to turn on the Windows Defender and resolve the Error 577 problem. While the last method works fine, be aware that you need to get rid of any trial version of security software or leftover registry and files to resolve it finally.
