I upgraded TeamCity 3.1.1 to 3.1.2 today. The upgrade went fine.
I have one minor issue with the upgrade process that I believe happened in the previous upgrade (3.1 to 3.1.1):
if you have more than one build agent, build agents other than the default build agent are disabled after the
upgrade. I had forgotten about this and it took me several minutes to realize why my 2nd build agent was
Suggestion: either document the fact that this will happen as part of the upgrade process or have the upgrade
process recreate the state of all build agents before the upgrade.