Windows Tray Notifier
You will need to upgrade windows tray notifier by uninstalling it and installing it again. Unfortunately, autoupgrade auto-upgrade will not work due to issues in old version of Windows Tray Notifier.
Open API Changes
Several return types have changes in TeamCity open API, so plugins might need recompilation against new TeamCity version to continue working.
Also, some API was deprecated and will be discontinued in later releases. It is recommended to update plugins not to use deprecated API.
Changes from 6.0.2 to 6.0.3
No noteworthy changes