Postgres error "invalid value for parameter "TimeZone": "UTC""

I had the same problem using the Postgres.app from Heroku. Rebooting my Mac solved it.

Restarting postgresql works.

To restart if you've installed it using homebrew, brew info postgresql will tell you to:

launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

Try restarting the server. I updated Postgresql through Homebrew but forgot to restart the server and got this same problem. I believe it's due to the client and server versions not matching. psql started with:

$ psql
psql (9.1.4, server 9.1.2)
Type "help" for help.

brew services restart postgresql