In one of my lab machines I was sifting through the log files and came across Event ID 12000 as shown below. As this lab machine does not have internet access at all, the error was a bit strange and no other alerts were raised. Nothing out of the ordinary was done besides running a few commands to check databases and users.
Running a new update for Exchange and rebooting, I did not notice this informational alert and maybe there was a leak into memory or something that triggered it but running the same set of commands that I ran previously, no event ID 12000 logged.
Not sure if this is just a false positive as I cannot find anything to try and remediate it or reproduce it.
Hope it helps.