Exchange 2013 Hybrid error when selecting 365 tab on ECP

Raymond Turrell 21 Reputation points
2021-02-17T19:41:56.773+00:00

Hi all
Hope you can help.
We have Exchange 2013 and I've run the hybrid the migration wizard with no errors at all.
My next step was to try to migrate a mailbox in ECP selecting the Office 365 tab and this is where I am stuck.
I see the following error...

login.microsoftonline.com refused to connect.

If I use a private browsing window then it prompts for a login and I pop in the main 365 admin account, I then get the same error.

I have ensured that all accounts I use have the Organization Management and Recipient Management role. I have confirmed that the MRSProxy service is on.

Really not sure what to do next to resolve this and would really appricate any help you can offer.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
7,435 questions
Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
1,959 questions
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Accepted answer
  1. KyleXu-MSFT 26,226 Reputation points
    2021-02-18T03:10:59.757+00:00

    @Raymond Turrell

    I would suggest you login https://outlook.office365.com/ecp/ then try to migrate mailboxes directly.

    The conversion between Exchange on-premises and Office 365 tab is unstable, it also controlled by Brower settings, such as saved password and cookies setting.


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  1. Raymond Turrell 21 Reputation points
    2021-02-19T10:28:11.613+00:00

    Fantastic, thank you so much. Turned out our remote endpoint was wrong but fixed that and all looks great now.

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