How to fix
“Windows could not start the Windows Defender Service service on Local Computer” Error
on Windows

I can’t launch Windows Defender as “Windows could not start the Windows Defender Service service on Local Computer. Error 577” message pops up. Disabled my anti-virus and tried to rerun the program but to no avail. I’d appreciate your help.

“Windows could not start the Windows Defender Service service on Local Computer” notification is the error message some Windows 10 users may encounter. Usually, this problem occurs due to conflicting Windows Defender program with third-party tools present on the system.

Since the introduction of the utility the program, Microsoft has warned about such issues and, likewise, suggested using only one tool: either Defender or a third-party tool. On the other hand, the software does not cause troubles while cooperating with malware elimination tools, e.g. Malwarebytes Anti-malware.

Furthermore, though the program may conflict with certain anti-virus tools, it does not negate them entirely. In fact, this Windows Defender error 577 appears a result of the external program modifying its registry files. Thus, let us provide solutions. 

Option 1. Use Registry Editor to fix Windows Defender Error 577

Step 1.

1. Click on Windows key+R.
2. Type regedit.
3. Once the program launches, enter the following path: HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender
4. Once the folder expands, you will find two registry files named DisableAntiSpyware and DisableAntiVirus on the right side of the panel.
5. Double click on both of them and check that DWORD (32-bit) value is set to 1. If necessary, change it to 1 from 0 and click OK.
6. Restart the device, if a notification prompts.

Step 2.

Due to these changes, another notification may appear: “This app is turned off by group policy.” Follow these steps:

1. Click on Start button and type local group.
2. Choose Edit group policy suggestion.
3.  Select Computer Configuration. Then expand Administrative Templates. Go to Windows components.
4. Find Windows Defender.
5. On the right side of the panel, you will see option Turn off Windows Defender. Double- click and place the checkmark on Disabled option. Finish the action by clicking Apply and OK.
6. Launch Windows Defender.

Option 2. Ensure the protection of your computer

Some users complain that they the error appears, but they cannot find the software listed in Registry Editor or Local Group Policy components. Make sure there is no malicious presence on the system. In case, you suspected unusual behavior, scan the computer with malware elimination utility in Safe Mode. Besides Advanced settings in the pre-boot mode, you can activate the mode via these steps:

1. Click on Start button.
2. Type system configuration.
3. Launch the program. Enter Boot section and mark Safe Boot option. Click Apply and then OK. The next time you boot the computer, it will launch in Safe Mode. To deactivate it, remove the checkmark from Safe Boot and restart the PC.