(Updated) Microsoft 365 Copilot transition to the cloud.microsoft domain [MC1286300]

Message ID: MC1286300 (Updated)

Updated April 30, 2026: We have updated the timeline. Thank you for your patience. 

[Introduction]

We’re updating the API endpoints used by Microsoft 365 Copilot to align with Microsoft’s ongoing transition to the cloud.microsoft domain. This change improves service reliability and security by ensuring Copilot-connected workloads use modernized Microsoft 365 network endpoints.

This update is part of a previously announced Microsoft domain unification initiative across Microsoft 365 services. This update does not introduce changes to the Microsoft 365 Copilot user interface and will not impact user experience, provided your environment follows published Microsoft 365 and Copilot network configuration requirements.

[When this will happen:]

General Availability (Worldwide, GCC): Rollout will begin in late April 2026 and is expected to complete by mid-May 2026 (previously late April).

[How this affects your organization:]

Who is affected:

• Microsoft 365 administrators managing network configurations for Microsoft 365 and Microsoft 365 Copilot
• Organizations using custom firewall, proxy, or endpoint filtering configurations within their tenant environment that restrict or interfere with WebSocket (WSS) connections

What will happen:

• APIs used by Microsoft 365 Copilot will transition from the legacy office.com domain to the cloud.microsoft domain.
• This change occurs at the service infrastructure level and is not visible to users.
• No changes to the Microsoft 365 Copilot user interface or workflows are expected.
• The change is enabled by default and cannot be disabled
• If your organization has followed previously published Microsoft 365 and Microsoft 365 Copilot network connectivity requirements:
  • No action is required
  • No service impact is expected
• Organizations that restrict access to the cloud.microsoft domain or restrict WSS connectivity may experience Microsoft 365 Copilot performance or reliability issues

[What you can do to prepare:]

• Confirm that traffic to *.cloud.microsoft is included in your Microsoft 365 endpoint allow list.
• Verify that WSS connections to *.cloud.microsoft destinations are not blocked or interfered with.
• Exempt traffic to *.cloud.microsoft from intrusive network actions such as:
  • TLS decryption
  • Packet inspection
  • Network-level DLP
• Review Microsoft 365 network connectivity guidance:
  • Microsoft 365 endpoints
  • Microsoft 365 Copilot connectivity requirements
• Communicate this change to your networking and helpdesk teams.
• Run the Microsoft 365 Copilot Network Connectivity Test: Microsoft 365 Copilot Network Connectivity Test.

[Compliance considerations:]

No compliance considerations identified, review as appropriate for your organization.

Source: Microsoft

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