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Why Does Exchange Online Show Object Reference Errors When Changing Public Folder Permissions?
Microsoft Exchange Online currently faces a documented backend issue preventing administrators from modifying public folder permissions in specific hybrid environments. The system rejects new permission assignments through both the graphical interface and command-line tools.
Understanding Permission Errors
Administrators encounter immediate failures when updating public folder access rights. The Exchange Admin Center displays an “Error saving changes” message, while the Add-PublicFolderClientPermission PowerShell cmdlet generates an “Object reference Not Set to an Instance of an Object” error. This glitch prevents new assignments, but previously established access rights remain fully operational.
Affected Hybrid Configurations
The issue isolates itself to specific Microsoft Exchange tenant architectures. Administrators report that the permission failure depends entirely on the active hybrid configuration mode.
Mitigation and Next Steps
Microsoft community forums confirm this widespread tenant-level malfunction stems from recent system behavior rather than local misconfigurations. You should document the exact PowerShell error output, including the RequestId, to assist Microsoft Support. Testing the modifications against different public-folder mailboxes determines if the failure affects the entire tenant or specific databases.