Summary
To enhance security, exporting the Auth certificate and its private key by using the Export-ExchangeCertificate cmdlet is no longer supported. This update blocks this functionality. If it's necessary to export the Auth certificate together with its private key, you should use the Windows PowerShellExport-PfxCertificatecmdlet or use the MonitorExchangeAuthCertificate.ps1 script. This cmdlet must be run directly on the server that's running Exchange Server. For more information, see Export-PfxCertificate.
Resolution
To fix this issue, install the following security updates, as appropriate:
- Description of the security update for Microsoft Exchange Server 2016 CU23: October 14, 2025 (KB5066369)
- Description of the security update for Microsoft Exchange Server 2019 CU14: October 14, 2025 (KB5066368)
- Description of the security update for Microsoft Exchange Server 2019 CU15: October 14, 2025 (KB5066367)
- Description of the security update for Microsoft Exchange Server Subscription Edition RTM: October 14, 2025 (KB5066366)