Why would Public Folders display error "Cannot expand the folder. The set of folders cannot be opened...." suddenly 2 weeks ago on an Exchange 2016 o

[Amanda Harden]

About 2 weeks ago clients began to get an error attempting to open the Public Folders on our Exchange 2016 server. I made no changes to the server, however did notice that a Windows Update Monthly Quality Roll up for 2012 r2 (KB5031419) ran on the server that same day as the error began. I uninstalled that update and still having the same issue accessing the Public Folder Mailbox. No users can access Public Folders. And in OWA no Public Folders can be found. Best Regards, Amanda

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