CU12 was more than just a bundle of bug fixes; it introduced structural changes to the Exchange ecosystem:
Only production-supported OS versions are eligible. Do not install on preview builds. microsoft exchange server 2019 cumulative update 12 download
for Exchange 2019 hybrid servers, a benefit previously limited to older versions. Servicing Model Shift: CU12 was more than just a bundle of
The only trusted source for the binary files is the Microsoft Download Center: microsoft exchange server 2019 cumulative update 12 download
⚠️ Never download Exchange cumulative updates from third-party file hosting sites, torrents, or unverified sources. These files are a common vector for malware.