Summary
Microsoft Exchange Server 2019 CU15 adds TLS 1.3 support (except for SMTP) to existing Microsoft Exchange Server 2019 on-premises installations that are running on eligible systems (Windows Server 2025 and Windows Server 2022).
Resolution
To fix this issue, install the following cumulative update:
- Cumulative Update 15 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019
More information
For more information about how to configure specific TLS versions on Exchange Server, see Exchange Server TLS configuration best practices.