Migrate from 1.1.1 or older version, to 1.2.1

In calendar page, space administrator need to click on migrating button (only visible by him/her), and wait the page to reload. After reload, the events appear in the calendar. Data is successfully migrated.
Please, note that every space administrator, having a space with events created with older versions, need to do the migration process described here, to be able to see old events.