更新Microsoft Defender（以前称为Windows Defender）时，您可能会遇到错误代码0x80004004。当Windows Defender无法从Microsoft网站下载更新的定义时，就会发生这种情况。在这篇文章中，我们将确定潜在原因，并提供您可以尝试成功解决此问题的解决方案。

该错误可能会出现在您的计算机屏幕上，并显示一条消息：

Error 0x80004004: This app couldnt check for virus and spyware definition updates. The definition updates couldn’t be installed

由于同一系统上安装了另一个防病毒程序，可能会发生此错误。它可以通过阻止Windows Defender程序更新来产生冲突。此错误背后的另一个原因可能是缺少某些系统文件。糟糕的互联网连接也可能导致出现此错误。

修复 Microsoft Defender^{(Fix Microsoft Defender)}错误 0x80004004

如果您遇到此问题，您可以尝试以下我们推荐的解决方案（不分先后顺序），看看是否有助于解决问题。

1. 将 Windows Defender 服务设置^{(Set Windows Defender Service)}为自动^(Automatic)
2. 暂时禁用任何第三方防病毒程序
3. 通过命令提示符^{(Command Prompt)}手动更新Windows Defender
4. 直接下载Windows Defender定义包

让我们看一下关于列出的每个解决方案所涉及的过程的描述。

1]将Windows Defender服务设置^{(Set Windows Defender Service)}为自动^(Automatic)

请执行下列操作：

• 按Windows key + R调用“运行”对话框。
• 在 Run 对话框中，键入services.msc并按 Enter打开 Services^{(open Services)}。
• 在“服务^(Services)”窗口中，滚动并找到Microsoft Defender 防病毒服务^{(Microsoft Defender Antivirus Service)}。
• 双击^{(Double-click)}条目以编辑其属性。
• 确保服务属性窗口中^(Make)启动类型^{(Startup type)}菜单下的选项  设置为 自动^(Automatic)。
• 确认^(Confirm)更改启动类型时可能出现的任何对话框。
• 单击应用^(Apply)>确定^(OK)。

之后，再次重新启动更新，看看是否成功完成。否则^(Otherwise)，请尝试下一个解决方案。

2]暂时^{(Temporarily)}禁用任何第三方防病毒程序

在Windows Defender^{(Windows Defender)}的病毒定义更新过程中，安装在 Windows 10 PC 上的第三方安全程序也会产生冲突，导致错误 0x80004004^{(error 0x80004004)}。因此，在更新Windows Defender^{(Windows Defender)}之前禁用防病毒软件可以证明是一种解决方案。

您可以从程序设置^(Settings)页面暂时禁用 PC 上的任何第三方防病毒软件。更新过程完成后，您可以重新启用它以获得全面保护。

3 ]通过命令提示符^{(Command Prompt)}手动^{(] Manually)}更新Windows Defender

请执行下列操作：

• 按Windows key + R调用“运行”对话框。
• 在“运行”对话框中，键入cmd并按 Enter 以打开命令提示符。
• 在命令提示符窗口中，键入或复制并粘贴下面的命令，然后在每行后按Enter 。

cd /d "\Program Files\Windows Defender"

mpcmdrun.exe -signatureupdate

在执行命令时。您仍然有错误，您可以尝试下一个解决方案。

您还可以使用 PowerShell 更新 Windows Defender 定义^{(update Windows Defender definitions using PowerShell)}。

4]直接下载Windows Defender定义包

您也可以尝试手动下载最新的 Defender 定义并进行更新^{(manually download the latest Defender definitions and update it)}。

这是一个“静默安装”——当您双击下载的文件时似乎不会发生任何事情，但它会在后台安装。

希望这可以帮助！

相关帖子^{(Related post)}：Windows Defender 不会自动更新^{(Windows Defender not updating automatically)}。

Fix Microsoft Defender error 0x80004004 on Windows 11/10

When updating Microsoft Defender (formerly Windows Defender), you may encounter the error code 0x80004004. It happens when Windows Defender fails to download updated definitions from the Microsoft website. In this post, we will identify the potential cause and also provide the solutions you can try to successfully resolve this issue.

The error can appear on your computer screen with a message stating:

Error 0x80004004: This app couldnt check for virus and spyware definition updates. The definition updates couldn’t be installed

This error can occur due to another antivirus program installed on the same system. It can create conflicts by preventing the Windows Defender program from updating. Another reason behind this error could be some system files missing. A bad internet connection can also result in this error to appear.

Fix Microsoft Defender error 0x80004004

If you’re faced with this issue, you can try our recommended solutions below in no particular order and see if that helps to resolve the issue.

1. Set Windows Defender Service to Automatic
2. Temporarily disable any third-party antivirus program
3. Manually update Windows Defender via Command Prompt
4. Directly download Windows Defender definition package

Let’s take a look at the description of the process involved concerning each of the listed solutions.

1] Set Windows Defender Service to Automatic

Do the following:

• Press Windows key + R to invoke the Run dialog.
• In the Run dialog box, type services.msc and hit Enter to open Services.
• In the Services window, scroll and locate the Microsoft Defender Antivirus Service.
• Double-click on the entry to edit its Properties.
• Make sure that the option under the Startup type menu in the service’s properties window is set to Automatic.
• Confirm any dialog boxes which may appear when changing the startup type.
• Click Apply > OK.

After that, restart the update again and see if it completes successfully. Otherwise, try the next solution.

2] Temporarily disable any third-party antivirus program

Third-party security programs installed on your Windows 10 PC can also create conflicts causing the error 0x80004004 during virus definition update process of Windows Defender. So, disabling the antivirus before updating Windows Defender can prove to be a solution.

You can temporarily disable any third-party antivirus on your PC from the programs Settings page. After the update process is done, you can re-enable it for full protection.

3] Manually update Windows Defender via Command Prompt

Do the following:

• Press Windows key + R to invoke the Run dialog.
• In the Run dialog box, type cmd and hit Enter to open Command Prompt.
• In the command prompt window, type or copy and paste the command below and hit Enter after each line.

cd /d "\Program Files\Windows Defender"

mpcmdrun.exe -signatureupdate

On executing the command. you still have errors, you can try the next solution.

You can also update Windows Defender definitions using PowerShell.

4] Directly download Windows Defender definition package

You may also try to manually download the latest Defender definitions and update it.

This is a ‘silent install’ – nothing will appear to happen when you double-click the downloaded file, but it will be installed in the background.

Hope this helps!

Related post: Windows Defender not updating automatically.

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