Can't create calendar event with existing user

Hello guys,
I am new to Nextcloud. I installed v18.0.7 and Calendar v2.0.3
When I create meeting with myself only Calendar works perfect.

If I add any existing user to the meeting, nothing happens. I see only moving circle.
I checked email setting, they work fine (test email received). User can login to the system without any problem

Here is a log I suspect tells about some problems:

{“reqId”:“lw4nyTy4n8dE9BOfgWsV”,“level”:0,“time”:“2020-07-21T18:20:55+02:00”,“remoteAddr”:“84.230.160.213”,“user”:“andromak”,“app”:“no app in context”,“method”:“GET”,“url”:"/avatar/test%20user/32?v=0",“message”:“Deprecated event type for \OCP\Files::postWrite: Symfony\Component\EventDispatcher\GenericEvent”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0”,“version”:“18.0.7.1”}
{“reqId”:“yX2RNknhC394cbZUs8op”,“level”:0,“time”:“2020-07-21T18:21:57+02:00”,“remoteAddr”:“84.230.160.213”,“user”:“andromak”,“app”:“no app in context”,“method”:“PUT”,“url”:"/remote.php/dav/calendars/andromak/personal/696CE7AE-BA7A-4063-A0A6-5B43B9360E00.ics",“message”:“Deprecated event type for \OCA\DAV\CalDAV\CalDavBackend::createCalendar: Symfony\Component\EventDispatcher\GenericEvent”,“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0”,“version”:“18.0.7.1”}
{“reqId”:“yX2RNknhC394cbZUs8op”,“level”:0,“time”:“2020-07-21T18:21:57+02:00”,“remoteAddr”:“84.230.160.213”,“user”:“andromak”,“app”:“webdav”,“method”:“PUT”,“url”:"/remote.php/dav/calendars/andromak/personal/696CE7AE-BA7A-4063-A0A6-5B43B9360E00.ics",“message”:{“Exception”:“Sabre\DAV\Exception\NotFound”,“Message”:“Principal with name test%20user not found”,“Code”:0,“Trace”:[{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Tree.php",“line”:76,“function”:“getChild”,“class”:“Sabre\DAVACL\AbstractPrincipalCollection”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Tree.php",“line”:71,“function”:“getNodeForPath”,“class”:“Sabre\DAV\Tree”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAVACL/Plugin.php",“line”:621,“function”:“getNodeForPath”,“class”:“Sabre\DAV\Tree”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAVACL/Plugin.php",“line”:196,“function”:“getCurrentUserPrivilegeSet”,“class”:“Sabre\DAVACL\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/apps/dav/lib/Connector/Sabre/DavAclPlugin.php",“line”:52,“function”:“checkPrivileges”,“class”:“Sabre\DAVACL\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Schedule/Plugin.php",“line”:506,“function”:“checkPrivileges”,“class”:“OCA\DAV\Connector\Sabre\DavAclPlugin”,“type”:"->"},{“file”:"/var/www/nextcloud/apps/dav/lib/CalDAV/Schedule/Plugin.php",“line”:138,“function”:“scheduleLocalDelivery”,“class”:“Sabre\CalDAV\Schedule\Plugin”,“type”:"->"},{“function”:“scheduleLocalDelivery”,“class”:“OCA\DAV\CalDAV\Schedule\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Schedule/Plugin.php",“line”:384,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Schedule/Plugin.php",“line”:665,“function”:“deliver”,“class”:“Sabre\CalDAV\Schedule\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Schedule/Plugin.php",“line”:367,“function”:“processICalendarChange”,“class”:“Sabre\CalDAV\Schedule\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/apps/dav/lib/CalDAV/Schedule/Plugin.php",“line”:131,“function”:“calendarObjectChange”,“class”:“Sabre\CalDAV\Schedule\Plugin”,“type”:"->"},{“function”:“calendarObjectChange”,“class”:“OCA\DAV\CalDAV\Schedule\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Plugin.php",“line”:943,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/CalDAV/Plugin.php",“line”:801,“function”:“validateICalendar”,“class”:“Sabre\CalDAV\Plugin”,“type”:"->"},{“function”:“beforeCreateFile”,“class”:“Sabre\CalDAV\Plugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:1094,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php",“line”:525,“function”:“createFile”,“class”:“Sabre\DAV\Server”,“type”:"->"},{“function”:“httpPut”,“class”:“Sabre\DAV\CorePlugin”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:479,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->"},{“file”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:254,“function”:“invokeMethod”,“class”:“Sabre\DAV\Server”,“type”:"->"},{“file”:"/var/www/nextcloud/apps/dav/lib/Server.php",“line”:319,“function”:“exec”,“class”:“Sabre\DAV\Server”,“type”:"->"},{“file”:"/var/www/nextcloud/apps/dav/appinfo/v2/remote.php",“line”:35,“function”:“exec”,“class”:“OCA\DAV\Server”,“type”:"->"},{“file”:"/var/www/nextcloud/remote.php",“line”:165,“args”:["/var/www/nextcloud/apps/dav/appinfo/v2/remote.php"],“function”:“require_once”}],“File”:"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php",“Line”:118,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0”,“version”:“18.0.7.1”}

Can you please help to understand what is going on.

Great thanks for support.

There’s a bug with users that have special characters like spaces in their username.

great news.

I just created a new user without spaces.
It works fine.

What is the plan when it will be fixed? Same behavior in Nextcloud 19

Great thanks for support.

Follow issue https://github.com/nextcloud/server/issues/15641 for updates

Unfortunately that issue is already closed without any resolution for for almost 9 months.

I am using Nextcloud LTS version + recommended software Calendar and basic functionality is not working, it is not possible to use Calendar as for now.

For me it is a BIG concern to use the whole solution.