calendar row plugin missing error

I'm receiving the following error when accessing the calendar display:

Debug:
'calendar_plugin_style: The calendar row plugin is required when using the calendar style, but it is missing.'
in calendar_plugin_style->render() (line 234 of /var/www/html/sites/all/modules/calendar/includes/calendar_plugin_style.inc).

I had performed an update from D6 to D7. How do I fix this?