You receive an "Unable to display the folder" error message when you try to access a public folder in Outlook

When you try to access a public folder from a Microsoft Outlook client, either of the following symptoms may occur:

• You may receive the following error message:
  Unable to display the folder
• The folder may not appear in the list of public folders.

In Outlook, the Owner of a public folder can limit the ability to view the folder contents to Owners only. To do so, if you are a public folder Owner:

1. In Outlook, open the folder properties.
2. Click the Administration tab. Under This folder is available to, click the Owners Only option button. If you click the All Users with access permission option button, other users will be able to view the folder contents.

Exchange uses role-based permissions on public folders. You can set the following role-based permissions: Owner, Publishing Editor, Editor, Publishing Author, Author, Nonediting Author, Reviewer, Contributor, and None. You can also set custom permissions. By default, anyone who has a minimum of Reviewer permissions should be able to see the public folder and view its contents. However, when the Owners only permission is set on a public folder from an Outlook client, even users with sufficient access permissions cannot view the folder.

For example, imagine a top-level public folder that is named "Test". User A has Owner permissions. User B and User C have Publishing Editor permissions. User D has Editor permissions. If User A uses the Microsoft Outlook client to set the This folder is available to option to Owners only, users B, C and D can no longer access or view the folder that is named Test.