Can't run In-Place eDiscovery search for Exchange Online mailbox in Exchange Server 2019 or 2016 by using EAC

Symptoms

In a Microsoft Exchange hybrid deployment environment, when you try to run In-Place eDiscovery searches in Microsoft Exchange Server 2019 or 2016 for cloud-based mailboxes by using Exchange admin center (EAC) in the on-premises server, you receive the following error message, depending on the scenario:

Scenario 1

You're trying to search a remote mailbox that doesn't have an online archive enabled. In this scenario, you receive an error message that resembles the following example:

Export failed with error type: 'FailedToSearchMailboxes'. Details: The underlying connection was closed: An unexpected error occurred on a receive. Endpoint: https://mail.contoso.com:444/EWS/Exchange.asmx

Scenario 2

You're trying to search a remote mailbox that has an online archive enabled. The estimate of search results succeeds. However, when you try to copy the results to a discovery mailbox, the attempt fails and returns an error message that resembles the example:

Failed Search or Export, Mailbox:UserOne@contoso.com::Item:::DocumentId:::ItemId: with error: [FailedToGetRootFolders] Export failed with error type: 'FailedToGetRootFolders'. Message: ErrorNonExistentMailbox : No mailbox with such guid. Endpoint: https://mail.contoso.com:444/EWS/Exchange.asmx

Workarounds

It's a known issue in Exchange Server 2019 and 2016. To work around this issue, use either of the following methods:

Method 1

Use the Office 365 Security & Compliance Center to run the In-Place eDiscovery search for the Exchange Online mailboxes.

Method 2

If you still have a server that is running Microsoft Exchange Server 2013 that is installed in your on-premises organization, move the discovery mailbox to the Exchange Server 2013 server, and then try the search again.