"It is not possible to expand the folder" error when you try to access Exchange public folders in Exchange Online

Applies to: Exchange OnlineOutlook 2016Outlook 2013


When you use Microsoft Outlook 2013 or Outlook 2016 to access Microsoft Exchange Server public folders in Microsoft Exchange Online, you receive the following error message:
It is not possible to expand the folder. It is not possible to open folders. Microsoft Exchange is not available due to network issues or Exchange Server is disabled for maintenance


To resolve this issue, follow the steps that are listed at the following Microsoft website:


This issue occurs because the Exchange mailbox that holds the public folder doesn't have the Client Access Server (CAS) role enabled.
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