Microsoft has released Security Updates (SUs) for vulnerabilities found in:
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
SUs are available in a self-extracting auto-elev...
Updated May 08, 2023
Version 22.0
Blog Post
I ran into a strange problem - one of the exchange 2016 mailbox servers (+windows server 2016) with up-to-date OS and application suddenly stopped authenticating users regardless of the client used - Outlook, OWA, ActiveSync. Unfortunately, there was no time for thoughtful troubleshooting - the reboot solved the problem, further analysis showed that the time of the problem exactly coincided with the automatic renewal of the computer's certificate (using a domain CA), the specified certificate was not assigned to any of the exchange services.
Of course, I understand that Post hoc non est propter hoc, but however, previously there were no such incidents on any of the 24 mailbox servers (not counting DR), although certificates with this template (standard computer) are updated once a year.
P.S. Perhaps restarting MSExchangeServiceHost would be enough instead of restarting.
P.P.S. a completely similar server in the same DAG and "mirrored" to this one automatically updated its certificate the day before installing the March SU and no anomalies were noticed.