Merge branch 'main' into dhagarwal_working

Author: chrisda

defender-endpoint/TOC.yml

@@ -511,8 +511,8 @@
           href: troubleshoot-collect-support-log.md
         - name: Troubleshoot Microsoft Defender Antivirus settings
           href: troubleshoot-settings.md
-        - name: Troubleshoot Microsoft Defender Antivirus service startup problems
-          href: troubleshoot-service-startup-problems.md
+        - name: Troubleshoot Microsoft Defender Antivirus Security intelligence not getting updated
+          href: troubleshoot-security-intelligence-not-updated.md 
         - name: Troubleshooting Security Intelligence Updates from Microsoft Update source
           href: security-intelligence-update-tshoot.md
           displayName: Troubleshooting Security Intelligence Updates from Microsoft Update source

defender-endpoint/media/protection-definition-update-failed.png

@@ -4,7 +4,7 @@ description: Learn about Microsoft Defender Antivirus with other security produc
 ms.service: defender-endpoint
 ms.subservice: ngp
 ms.localizationpriority: medium
-ms.date: 10/17/2024
+ms.date: 01/10/2025
 ms.topic: conceptual
 author: emmwalshh
 ms.author: ewalsh
@@ -132,6 +132,12 @@ In order for Microsoft Defender Antivirus to run in passive mode, endpoints must
 
 - Endpoints must be onboarded to Defender for Endpoint. 
 
+- Windows Security Center Service must be enabled.
+
+> [!WARNING]
+> If the **Windows Security Center Service** is *disabled* on Windows Clients then Microsoft Defender Antivirus can't detect third-party antivirus installations and will stay **Active**.
+> This could lead to conflicts between the Microsoft Defender Antivirus and the third-party Antivirus, as both will attempt to provide active protection. This will impact performance and is not supported.
+
 > [!IMPORTANT]
 > - Microsoft Defender Antivirus is only available on devices running Windows 10 and 11, Windows Server 2022, Windows Server 2016, Windows Server 2019, Windows Server, version 1803 or newer, Windows Server 2016, and Windows Server 2012 R2.
 > - Passive mode is only supported on Windows Server 2012 R2 & 2016 when the device is onboarded using the [modern, unified solution](configure-server-endpoints.md). 

defender-endpoint/media/signature-update-failed.png

@@ -0,0 +1,75 @@
+---
+title: Troubleshoot Microsoft Defender Antivirus Security intelligence not getting updated
+description: Learn how to troubleshoot Microsoft Defender Antivirus Security intelligence not getting updated.
+author: emmwalshh
+ms.author: ewalsh
+manager: ewalsh 
+ms.date: 01/10/2025
+ms.topic: troubleshooting
+ms.service: defender-endpoint
+ms.subservice: ngp
+ms.localizationpriority: medium 
+ms.collection: # Useful for querying on a set of strategic or high-priority content.
+ms.custom: 
+- partner-contribution
+ms.reviewer: ewalsh
+search.appverid: MET150
+f1.keywords: NOCSH
+audience: ITPro
+---
+
+# Troubleshoot Microsoft Defender Antivirus Security intelligence not getting updated
+
+**Applies to:**
+
+- [Microsoft Defender XDR](/defender-xdr)
+- [Microsoft Defender for Endpoint Plan 1 and 2](microsoft-defender-endpoint.md)
+- [Microsoft Defender for Business](https://www.microsoft.com/security/business/endpoint-security/microsoft-defender-business)
+- [Microsoft Defender for Individuals](https://www.microsoft.com/microsoft-365/microsoft-defender-for-individuals)
+- Microsoft Defender Antivirus
+
+## Symptom
+
+When you update Microsoft Defender Antivirus security intelligence, you might see the error **Protection definition update failed**.
+
+:::image type="content" source="media/protection-definition-update-failed.png" alt-text="Screenshot of Protection definition update failed.":::
+
+These error codes might also appear:
+
+- 0x8024402c 
+- 0x80240022 
+- 0X80004002 
+- 0x80070422 
+- 0x80072efd 
+- 0x80070005 
+- 0x80072f78 
+- 0x80072ee2 
+- 0x8007001B 
+
+The following screenshot shows the error **Signature Update failed**.
+
+:::image type="content" source="media/signature-update-failed.png" alt-text="Screenshot showing signature update failed." lightbox="media/signature-update-failed.png":::
+
+## Solution
+
+1. Check the URLs required for the Security intelligence updates. You can get them via the firewall and/or proxy. See [Configure your network environment to ensure connectivity with Defender for Endpoint service](configure-environment.md).
+
+1. Ensure that Microsoft Defender Antivirus (MDAV) is your primary antivirus. If you have a third-party antivirus that uses the Windows Security Center (WSC) API, it will disable MDAV. When MDAV is disabled, updates can't occur.
+
+1. Given that MDAV is the primary antivirus and the services are running:
+
+    1. Check if updating Security Intelligence works when you manually download from [Latest security intelligence updates for Microsoft Defender Antivirus and other Microsoft antimalware?](https://www.microsoft.com/wdsi/defenderupdates)
+
+    1. If so, try updating through the Microsoft Malware Protection Center (MMPC).
+
+       Run the following PowerShell command as an administrator.
+
+       ```powershell
+          & "${env:ProgramFiles}\Windows Defender\MpCmdRun.exe" -SignatureUpdate -MMPC
+       ```
+
+    1. If this command works, the issue might be that the Security intelligence  [Fallback order](manage-protection-updates-microsoft-defender-antivirus.md#fallback-order) is set to a WSUS server without **Security intelligence** approved updates. Alternatively, the UNC share might be stale, or the Windows Update service might have issues.
+
+        1. To check the WSUS server that the machine goes to, review `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\WUServer (REG_SZ)`. Once you find the WUServer, check if that WSUS server has the MDAV security intelligence [(KB2267602 for MDAV and KB2461484 for SCEP)](microsoft-defender-antivirus-updates.md#security-intelligence-updates) approved.
+        1. To check the UNC share, review [Manage how and where Microsoft Defender Antivirus receives updates](manage-protection-updates-microsoft-defender-antivirus.md#create-a-unc-share-for-security-intelligence-and-platform-updates).
+        1. To check the status of the Windows Update service, review [Guidance for troubleshooting Windows Update issues](/troubleshoot/windows-client/installing-updates-features-roles/troubleshoot-windows-update-issues) and [Troubleshoot problems updating Windows](https://support.microsoft.com/windows/troubleshoot-problems-updating-windows-188c2b0f-10a7-d72f-65b8-32d177eb136c).