Merge pull request #9960 from v-tappelgate/AB#7936-W365BCDR

AB#7936: W365Ent BCDR known issues - update & fix

Author: v-tappelgate

.openpublishing.redirection.json

@@ -1,5 +1,10 @@
 {
   "redirections": [
+    {
+      "source_path": "support/windows-365/troubleshoot-windows-365-bcdr-known-isssues.md",
+      "redirect_url": "/troubleshoot/windows-365/windows-365-bcdr-known-issues",
+      "redirect_document_id": false
+    },
     {
       "source_path": "support/windows-client/windows-tss/gather-information-using-tss-user-experience.md",
       "redirect_url": "/troubleshoot/windows-client/windows-tss/collect-data-analyze-troubleshoot-sys-management-components-scenarios",

support/windows-365/toc.yml

@@ -70,4 +70,4 @@ items:
   - name: Windows 365 BCDR
     items:
     - name: Windows 365 BCDR known issues
-      href: windows-365-bcdr-known-issues.md      
+      href: windows-365-bcdr-known-issues.md

support/windows-365/troubleshoot-windows-365-bcdr-known-isssues.md

@@ -0,0 +1,32 @@
+---
+title: Windows 365 BCDR Known Issues
+description: Learn about known issues that involve Windows 365 disaster recovery, including workarounds and updated fixes.
+ms.reviewer: kaushika; aradinger; v-appelgatet
+ms.date: 10/16/2025
+ms.topic: troubleshooting-known-issue
+ms.service: windows-365
+ms.custom:
+  - pcy:WinComm User Experience
+  - sap:Windows 365 Enterprise Edition\Cloud PC Recovery\Disaster Recovery Issues
+---
+# Windows 365 BCDR known issues
+
+This article addresses a known issue that's related to Windows 365 Business Continuity and Disaster Recovery (BCDR) scenarios.
+
+## Classic Outlook is corrupted after disaster recovery failover or failback
+
+After you restore a Cloud PC from a snapshot during a disaster recovery failover, or upon failing back to the primary region after the disaster, users might encounter an error message when they start classic Outlook.
+
+This issue occurs because the Outlook offline cache becomes corrupted because the client and the server become out of sync during a failover. The client on the snapshot reflects a past state relative to the server's current status. The process of resynchronizing the Offline Storage Table (OST) file can take time.
+
+This process doesn't cause any data loss.
+
+### Workaround
+
+After you complete a failover or failback operation, delete the Cloud PC's OST file.
+
+This action forces Outlook to rebuild the search index and the offline cache of the mailbox. This process doesn't cause any data loss.
+
+### Resolution
+
+Use the new Outlook app. The new Outlook app uses a different caching mechanism that eliminates this synchronization issue.