Purpose: ITIC and ITIS have been engaged for two weeks with Microsoft support to fix an issue where a Teams user is unable to leave a VM for a on-prem Skype for Business user. Microsoft technicians yesterday discovered that a Lync/SFB component that Exchange uses was not updated. An issues was discovered with the Lync Unified Communications Managed API (UCMA) and a patch developed and deployed several years ago. That was never ported to Exchange. The fix was to install the Lync update on Exchange. It detects that the UCMA is running and out of date, and applies the update.
Impact: Modern clients maintain connection to Exchange as DBs move between servers. The only place this is noticeable is in PowerShell. If a server is in maintenance, some PowerShell cmdlets that IT use will fail.
Affected: Given the redundant nature of Exchange, neither end users nor mail delivery is affected.