The way the calendar data is stored in the database changed with ownCloud 9.0.
So, before upgrading, it might be a good idea to backup all existing calendars and addressbooks (e.g. with calcardbackup), in case you run into problems.
The way the calendar data is stored in the database changed with ownCloud 9.0.
So, before upgrading, it might be a good idea to backup all existing calendars and addressbooks (e.g. with calcardbackup), in case you run into problems.