Hi @Nur Hossain ,
According to the Microsoft official document we could know that it is possible to switch to Modern Hybrid (Hybrid Agent) after successfully configuring Classic Hybrid. But we only recommend doing this if you are blocked from migrating to Microsoft 365 or Office 365 after this setup is complete. Because not all hybrid features or experiences are supported with the Hybrid Agent. If you are successfully migrating mailboxes your users are experiencing hybrid features and chose to revert to Modern Hybrid.
The following are the constraints you need to consider in Exchange Modern Hybrid:
- Hybrid Modern Authentication is not supported with the Hybrid Agent. Customers will need to leverage the Classic Exchange Hybrid Topology and publish AutoDiscover, EWS, ActiveSync, MAPI and OAB endpoints for hybrid Modern Authentication to function with various Outlook clients.
- For Teams' Calendaring features that require access to on-premises mailboxes, it's recommended that you leverage the full Classic Exchange Hybrid Topology.
- Message Tracking and Multi-mailbox search do not traverse the Hybrid Agent. These Hybrid features require the classic connectivity model where Exchange Web Services (EWS) and Autodiscover are published on-premises and are externally available to Microsoft 365 and Office 365.
- The Hybrid Agent supports a single migration endpoint with the service default limits. Multiple migration endpoints utilizing your custom endpoint/URL is not supported.
- The Hybrid Agent supports a single Exchange organization. Multiple Exchange organizations hybrid is not supported.
If you have weighed the pros and cons of switching from Classic to Modern and choose to proceed, you could do this by deleting your existing migration batches and migration endpoint and re-running the Hybrid Configuration wizard and selecting Modern Hybrid.
About Exchange Modern Hybrid requirements and restrictions to be considered you could refer to: Microsoft Hybrid Agent
In addition, we also need to meet the prerequisites for hybrid deployment: Hybrid deployment prerequisites
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