Hello there Tom.O’Brien. We have read your message. We try to help you. http://kb.mozillazine.org/Migrating_from_Sunbird_to_Lightning https://support.mozilla.org/en-US/kb/exporting-and-sharing-a-calendar https://wiki.mozilla.org/Calendar:FAQ In Sunbird export the entire calendar into the iCalendar format. In Lightning create a new local calendar for each Sunbird calendar and import the corresponding iCalendar file. Ensure that the new calendar is actually set to display events using the checkbox in the calendar list in the left pane. The Open Calendar File function is just a shortcut for the Network calendar with local path function. Both result in a new calendar that is linked to the file.The iCalendar file can be shared much easier between different computer systems or Lightning versions or both compared to the built-in database file. Greetings Firefox Volunteer.