ISSUE: The remote server is unhealthy

Overview

Mailbox Move workflow step may fail with the following error:

EXCEPTION: System.Management.Automation.RuntimeException: {"ClassName":"Microsoft.Exchange.MailboxReplicationService.RemoteResourceUnhealthyTransientException","Message":"The remote server is unhealthy due to 'The remote server is unhealthy due to ''.'.","Data":
{"Microsoft.Exchange.MailboxReplicationService.DataContext":{"Contexts":["--------","--------\r\nRemote server: https://endpoint/EWS/mrsproxy.svc Server36.beth-el.com (15.0.1497.47 ServerCaps:, ProxyCaps:, MailboxCaps:, legacyCaps:0400001F7FFFFFCB07FFFF)",
"Remote server: net.tcp://server.prod.outlook.com/Microsoft.Exchange.MailboxReplicationService Server.eurprd09.prod.outlook.com (ServerCaps:3FFFFFFF, ProxyCaps:7FFFFFFFFFFFFFC7DD2DFDBF5FFFFFCB07EFFF, MailboxCaps:, legacyCaps:3FFFFFFF)","--------","--------\r\nRemote server:
 https://Endpoit/EWS/mrsproxy.svc Server

Solution

This may be just a Transient error on the Microsoft O365 side or OnPrem Exchnage server. Restart of the Move Mialobx step in couple of minutes should resolve the issue.

To prevent this issues it's recommend to follow microsot5 best practices:

1. Exchange server meets hardware requirements:  Exchange 2013 system requirements: Exchange 2013 Help | Microsoft Learn

2. Check the Exchange server health: Manage health sets and server health: Exchange 2013 Help | Microsoft Learn

3. Follow Microsoft best practice for mailbox migrations: Microsoft 365 and Office 365 migration performance and best practices | Microsoft Learn