It is not possible to expand the folder error when accessing public folders in Exchange Online
Original KB number: 3027606
Symptoms
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
Resolution
To resolve this issue, follow the steps that are listed in Configure legacy on-premises public folders for a hybrid deployment.
More information
This issue occurs because the Exchange mailbox that holds the public folder doesn't have the Client Access Server (CAS) role enabled.
Still need help? Go to Microsoft Community.
Feedback
Coming soon: Throughout 2024 we will be phasing out GitHub Issues as the feedback mechanism for content and replacing it with a new feedback system. For more information see: https://aka.ms/ContentUserFeedback.
Submit and view feedback for