[solved] Calendar: Can't create more than one calendar

PROBLEM: I can’t create more than one calendar per user.

Nextcloud version 11.0.1 (stable):
Operating system and version (Ubuntu Server 16.04):
Apache version Apache 2.4.18:
PHP version 7.0:

  1. I’ve enabled Calendar app.
  2. I changed the name of default calendar: “default” --> “calendar 1”.
  3. I can’t create other calendars:
    I click on “new calendar” --> insert the name of new calendar (eg. calendar 2) --> click on create --> nothing happens.

Logging:

Sabre\DAV\Exception\NotFound: HTTP/1.1 404 Node with name 'calendar-2' could not be found

0.  /var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Tree.php - line 76: OCA\DAV\CalDAV\CalendarHome->getChild('calendar-2')
1.  /var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 939: Sabre\DAV\Tree->getNodeForPath('calendars/admin...')
2.  /var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php - line 336: Sabre\DAV\Server->getPropertiesForPath('calendars/admin...', Array, 0)
3.  [internal function] Sabre\DAV\CorePlugin->httpPropFind(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
4.  /var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php - line 105: call_user_func_array(Array, Array)
5.  /var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 479: Sabre\Event\EventEmitter->emit('method PROPFIND', Array)
6.  /var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 254: Sabre\DAV\Server->invokeMethod(Object(Sabre\HTTP\Request), Object(Sabre\HTTP\Response))
7.  /var/www/nextcloud/apps/dav/lib/Server.php - line 227: Sabre\DAV\Server->exec()
8.  /var/www/nextcloud/apps/dav/appinfo/v2/remote.php - line 30: OCA\DAV\Server->exec()
9.  /var/www/nextcloud/remote.php - line 165: require_once('/var/www/nextcl...')
10. {main}

Can someone help me?
Thanks.

I have deleted the data of the calendar tables and I solved.

Wich calendar tables data do you mean? I have no idea wich tables you mean.

@ancdie probably refers to the database tables.
oc_calendars and oc_calendarobjects

But be aware: Deleting the content of these tables will delete all calendars and all objects!

oc_calendarchanges
oc_calendarobjects
oc_calendars
oc_calendarsubscriptions