owncloud 9.0.2 destroyed

Again, the recent own cloud 8 -> 9 updates remained difficult. Modifying the database helped:

update oc_appconfig set configvalue = 'dav/appinfo/v1/webdav.php' where appid = 'core' and configkey = 'remote_files';
update oc_appconfig set configvalue = 'dav/appinfo/v1/webdav.php' where appid = 'core' and configkey = 'remote_webdav';
update oc_appconfig set configvalue = 'dav/appinfo/v1/caldav.php' where appid = 'core' and configkey = 'remote_calendar';
update oc_appconfig set configvalue = 'dav/appinfo/v1/caldav.php' where appid = 'core' and configkey = 'remote_caldav';
update oc_appconfig set configvalue = 'dav/appinfo/v1/carddav.php' where appid = 'core' and configkey = 'remote_contacts';
update oc_appconfig set configvalue = 'dav/appinfo/v1/carddav.php' where appid = 'core' and configkey = 'remote_carddav';
update oc_appconfig set configvalue = 'dav/appinfo/v1/carddav.php' where appid = 'core' and configkey = 'remote_contactsplus';

But only to discover that the new calendar entries were corrupt as found by others

/* show old calendars and count */
SELECT o.calendarid, c.userid, c.displayname, c.uri, COUNT(o.calendarid)
FROM oc_clndr_objects o
JOIN oc_clndr_calendars c ON o.calendarid = c.id
GROUP BY calendarid
ORDER BY c.userid, c.displayname;
/* show new calendars and count */
SELECT o.calendarid, c.principaluri, c.displayname, c.uri, COUNT(o.calendarid)
FROM oc_calendarobjects o
JOIN oc_calendars c ON o.calendarid = c.id
GROUP BY calendarid
ORDER BY c.principaluri, c.displayname;

Maybe I give up on own cloud now.