How to fix
“Virus and Spyware definitions couldn’t be updated” error
on Windows

I can’t update Windows Defender. I don’t know why this is happening, but it is showing “Virus and spyware definitions couldn't be updated” error all the time. Can anyone help me out?

Smart Windows 10 users regularly check the condition of Windows Defender. Although this version of Windows OS has an automatic system update feature, which is responsible for both installation of patch updates and security updates, sometimes it fails to work.

Due to this purpose, Windows Defender may lack for the latest virus and spyware definitions putting the system into a high-risk of malware attack. To prevent this from happening, security experts recommend installing Windows Defender definitions manually on a regular basis.

As we have already pointed out, Windows Defender Antivirus gets updates as part of Windows Update. Therefore, configure the settings to install Windows Updates manually and you should be OK. Additionally, you can manually download the latest definitions or pre-release definitions from this page.

However, updating Windows Defender is a complicated task, which may end up with failure. Many people reported an error, which says that “Virus and spyware definitions couldn’t be updated.” The pop-up provides the following additional information:

This application couldn’t check for virus and spyware definition updates. Check your Internet and network connection and try again.
Error Code: 0x800704e8
Error description: The definition updates couldn’t be installed. Please try again later.

“Virus and spyware definitions couldn’t be updated” error on Windows Defender can be marked with the following error codes: 0x8024402c, 0x80240022, 0x80004002, 0x80070422, 0x80072efd, 0x80070005, 0x80072f78, 0x80072ee2, 0x8007001B.

According to Windows 10 users, Windows Update Troubleshooter doesn’t help to isolate the culprit of “The definition updates couldn’t be installed. Please try again later” error. If you haven’t tried it yet, navigate to Settings -> Update & Security -> Troubleshoot -> Windows Update. If the troubleshooter did not help to fix “The definition updates couldn’t be installed. Please try again later” error for you, try the following fixes:

Fix 1. Remove third-party antivirus

If your PC has been upgraded to Windows 10 from Windows 7, it’s very likely that the culprit of the problem is third-party antivirus, such as Norton or AVG. Windows 7 tend to come with Norton antivirus preinstalled. The application is notorious in terms of removal.

You have to options for complete third-party antivirus removal. You can either run a scan with software removal tool, such as [rev id="Perfect Uninstaller"] or open Windows Registry Editor and remove the corresponding folders and files.
To access Registry Editor, press Windows key + R, type regedit, and press Enter. Click Yes on the confirmation window to open the editor.

Fix 2. Update Windows Defender using Command Prompt

1. Right-click on Windows key and select Command Prompt (Admin).
2. Copy and paste the below given commands in the run and press Enter after each:

%PROGRAMFILES%\\Windows Defender\\MPCMDRUN.exe
%PROGRAMFILES%\\Windows Defender\\MPCMDRUN.exe

The first command removes all current Windows Defender definitions, while the next one fully updates Windows Defender antivirus.

Fix 3. Remove Windows Defender Signature File

1. Turn off Windows Defender completely.
2. Press Windows key + R, type Msiexec /x {A5CC2A09-E9D3-49EC-923D-03874BBD4C2C}, and press Enter.

3. Once the command is executed, open Windows Defender and click Update button.
4. If the update process successfully finished, reboot the system.