In your Monitors, there was a tab called Alert conditions. We felt that the name was not describing correctly what the tab is about. After all you do not define conditions here for generating alerts, but you define conditions for the detection and generation of errors. Hence the tab got a new name and now is called Error conditions. The functionality and the content of the tab is still the same!
In case you are working with Monitor templates - these will also have the new tab name to be consistent.