“The remote server returned an Error 404” or "HTTP request has exceeded the allotted timeout" error when you move a mailbox from on-premises Exchange Server to Exchange Online

PROBLEM

When you try to move or onboard a mailbox from your on-premises Exchange environment to Exchange Online in Office 365 in an Exchange hybrid deployment, you receive an error message that resembles one of the following:

• Error(s): The call to https://mail.<DomainName>.com/ews/mrsproxy.svc failed because no service was listening on the specified endpoint
  
  Error details:
  There was no endpoint listening at https://mail.<DomainName>.com/ews/mrsproxy.svc that could accept the message. This is often cause by an incorrect address or SOAP action. The remote server returned an error 404 not found.

• Error: MigrationTransientException: The call to ‎'https://mail.<DomainName>.com/EWS/mrsproxy.svc‎' timed out.
  
  Error details:
  The request channel timed out while waiting for a reply after 00:00:00.0020000. Increase the timeout value passed to the call to Request or increase the SendTimeout value on the Binding. The time allotted to this operation may have been a portion of a longer timeout. --> The HTTP request to ‎'https://mail.<DomainName>.com/EWS/mrsproxy.svc‎' has exceeded the allotted timeout of 00:00:00.0020000.

• Error: MigrationTransientException: The call to 'https://mail.contoso.com/EWS/mrsproxy.svc' failed because no service was listening on the specified endpoint.
  
  Error details: There was no endpoint listening at https://mail.contoso.com/EWS/mrsproxy.svc that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details.
  
  The remote server returned an error: (404) Not Found. --> The call to 'https://mail.contoso.com/EWS/mrsproxy.svc' failed because no service was listening on the specified endpoint.

However, you may still be able to move other mailboxes successfully. 

10/23/2020 : 20:09 UTC : bluehawk prod test

CAUSE

This problem may occur if the ExchangeGUID property of the Exchange Online MailUser object does not match the ExchangeGUID property of the on-premises mailbox. To successfully move a mailbox, the value of the ExchangeGUID property in the Exchange Online mailbox and in the associated on-premises remote mailbox must match.

SOLUTION

Set the ExchangeGUID property of the mail-enabled user in Exchange Online to match the ExchangeGUID property of the corresponding on-premises mailbox, and then retry the move. To do this, follow these steps:

1. Retrieve the value of the ExchangeGUID property for the on-premises mailbox that you want to move. To do this, open the Exchange Management Shell on the on-premises server, and then run the following command:

   Get-Mailbox <MailboxName> | Format-List ExchangeGUID 

   Make a note of the value. You'll need it later in step 2B.

2. Connect to Exchange Online by using remote PowerShell. For more information, see Connect to Exchange Online using Remote PowerShell. Then, do the following:

   1. Determine the value of the ExchangeGUID property of the mail-enabled user in Exchange Online. To do this, run the following command:

      Get-MailUser -Identity <UserName> | fl displayname,ExchangeGuid 

   2. Set the value of the ExchangeGUID property of the mail-enabled user in Exchange Online to match the ExchangeGUID property of the on-premises mailbox. To do this, run the following command:

      Set-MailUser -Identity <UserName> -ExchangeGUID <Value Retrieved From Step 1> 

3. Retry the move.

MORE INFORMATION

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