The matching ContainerNotFound and HTTP 404 failures across the official links, bootstrap installer, and an existing installation indicate a current Microsoft-hosted SPMT installer-resource incident; check Microsoft 365 Service health and report the incident rather than repeatedly reinstalling or repairing Windows.
Current status and download link
As of November 2, 2026, a current Microsoft Q&A report documents the same SPMT/Migration Manager installer-resource failure. It identifies ContainerNotFound, HTTP 404, and 0x08000301 as a download/build-retrieval problem and recommends checking Service health and opening a support case when the official paths remain unavailable.^1^
Microsoft’s documentation still designates these as the current installation links:
- GA/First Release:
https://aka.ms/spmt-ga-page
- Public Preview:
https://aka.ms/spmt-beta-page
Both are listed on the canonical installation page.^2^ The current release notes also identify [IP Address] as the latest GA and preview build and point to those same links.^3^
Therefore:
- The documented location has not moved.
- There is currently no independently documented working replacement URL.
- The preview is not a workaround while its Microsoft-hosted container also returns 404.
Report the outage
- In the Microsoft 365 admin center, open Health → Service health.
- Look for a SharePoint Online or migration-related advisory.
- If no relevant incident appears, use Report an issue from Service health or open Support → New service request.^4^
Include:
-
ContainerNotFound and 0x08000301
- The failing GA and preview URLs
- UTC timestamp and Request ID
- Confirmation that the failure occurs with a colleague’s setup and an existing installation
- Results from another network, if available
Service health is tenant-specific and is the primary incident channel; the public service-status page is the fallback if the admin center itself is unavailable.^5^
Retirement and Migration Manager
SPMT is not documented as retired. Microsoft still publishes current SPMT release notes and describes it as the supported downloadable tool for file-share and SharePoint Server migration.^6^
Migration Manager is an alternative only for supported sources:
- File share source: Migration Manager is a suitable alternative. Open the SharePoint admin center → Migration Center → File shares, install an agent, and create the migration task there.^7^
- SharePoint Server source: Migration Manager does not support SharePoint Server content; Microsoft directs that scenario to SPMT.^8^
Offline installer and existing installation
Microsoft’s current SPMT installation documentation provides bootstrap/web installation links but does not document a standalone offline installer. A setup executable copied from another computer still needs to retrieve remote builds, matching the 404 shown during Preparing.
Likewise, an installed copy can depend on its online deployment/update location. ClickOnce deployments can check a web update location at launch, so a broken publishing endpoint can prevent startup.^9^
Do not manually copy or modify installer/cache directories. Wait for Microsoft to restore the endpoint, then:
- Launch the existing installation again.
- If it remains broken, uninstall SPMT from Settings → Apps → Installed apps.
- Reinstall from the canonical GA page.
- Only if installation still fails after the URLs return normally, verify x64 Windows, .NET Framework 4.6.2 or later, and the x64 Visual C++ Redistributable as documented in Microsoft’s installation troubleshooting guidance.^10^
References
- Can not install SPMT (share point migration tool)
- Step 1: Install the SharePoint Migration Tool (SPMT)
- Release Notes: SharePoint Migration Tool (SPMT)
- How to check Microsoft 365 service health
- Microsoft 365, Dynamics 365 & Power Platform incident readiness for Microsoft Engage Center
- Overview of the SharePoint Migration Tool (SPMT)
- Overview: Migrate your file shares to Microsoft 365
- Frequently Asked Questions: Migration Manager File Share
- ClickOnce deployment and security
- Troubleshooting SPMT installation issues