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Office 365: Unable to Open Archive Mailbox | Wait 30 Minutes

In the recent hybrid migration, I experienced this so sharing with you all here.


This mailbox was a big mailbox with archive mailbox on Exchange 2013 in a hybrid setup.

We migrated this mailbox to office 365.

It got migrated perfectly. Absolutely no issues in migrating.

Outlook | OWA | ActiveSync connected as expected.

When user expanded the archive user got the following message popup



Cannot expand the folder. The set of folders cannot be opened. Microsoft Exchange is currently busy. If this message is still displayed in 30 minutes, contact your Exchange administrator.



We waited for 30 minutes and archive mailbox started opening as expected.



There is nothing to be panic here. Keep you cool and wait for 30 minutes.

This is one of the reason why we need to migrate mailboxes in the night or after business hours.

This is not an issue but it is by design.



Prabhat Nigam

Microsoft MVP | Exchange Server


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