Dissapearing Calendar invitations

Hello!
we seem to have an issue with our owncloud (v. 10.9.1 - Ubuntu 18.04.6) and calendar invitations created with Thunderbird.
this is what happens: we create an new appointment in Mozilla Thunderbird, (on Linux Mint 20.2) and invite a user on the same domain and the same owncloud server to the appointment. after clicking Save and Send the appointment just dissapears from the Thunderbird Calendar view. We dig into this issue and we find that creating a meeting thru the Owncloud web interface>Calendar and adding an Attendee creats the same issue: after clicking “Create” the appointment dissapears and is nowhere to be found in the view/browser/client.

while checking the owncloud.log file i find a few things:
1)/remote.php/dav/calendars/John%20Doe/John-Doe/ownCloud-LJ88LEGH4UBFV700KIF1H.ics:
seems that the URL also gets changed with %20, where the space is in the username. (the space gets replaced with %20).

  1. error: 1.1 404 Principal with name Invited%20User not found:
    most of our usernames contain spaces (…i know) and in the logs i see it gets changed to john%20doe and then it cant find it? (the space also gets replaced with %20).

Ofcourse we verified that the users actually do exist.
this issue happens with multiple users and seemingly only when there is a space in the username.

So, if the space really is the issue, how do we go about and fix this? changing usernames is not possible, i have found.

{“reqId”:“9Rbuir8OnYOFTMvMWSE5”,“level”:0,“time”:“2022-03-21T20:19:22+00:00”,“remoteAddr”:“x.x.x.x”,“user”:“John Doe”,“app”:“webdav”,“method”:“PUT”,“url”:"/remote.php/dav/calendars/John%20Doe/John-Doe/ownCloud-LJ88LEGH4UBFV700KIF1H.ics",“message”:“Exception: HTTP/1.1 404 Principal with name Invited%20User not found: {“Exception”:“Sabre\\DAV\\Exception\\NotFound”,“Message”:“Principal with name Invited%20User not found”,“Code”:0,“Trace”:”#0 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/Tree.php(78): Sabre\\DAVACL\\AbstractPrincipalCollection->getChild()\n#1 \/var\/www\/owncloud\/apps\/dav\/lib\/Tree.php(51): Sabre\\DAV\\Tree->getNodeForPath()\n#2 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/Tree.php(73): OCA\\DAV\\Tree->getNodeForPath()\n#3 \/var\/www\/owncloud\/apps\/dav\/lib\/Tree.php(51): Sabre\\DAV\\Tree->getNodeForPath()\n#4 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAVACL\/Plugin.php(601): OCA\\DAV\\Tree->getNodeForPath()\n#5 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAVACL\/Plugin.php(199): Sabre\\DAVACL\\Plugin->getCurrentUserPrivilegeSet()\n#6 \/var\/www\/owncloud\/apps\/dav\/lib\/Connector\/Sabre\/DavAclPlugin.php(51): Sabre\\DAVACL\\Plugin->checkPrivileges()\n#7 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Schedule\/Plugin.php(472): OCA\\DAV\\Connector\\Sabre\\DavAclPlugin->checkPrivileges()\n#8 \/var\/www\/owncloud\/lib\/composer\/sabre\/event\/lib\/WildcardEmitterTrait.php(89): Sabre\\CalDAV\\Schedule\\Plugin->scheduleLocalDelivery()\n#9 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Schedule\/Plugin.php(350): Sabre\\DAV\\Server->emit()\n#10 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Schedule\/Plugin.php(627): Sabre\\CalDAV\\Schedule\\Plugin->deliver()\n#11 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Schedule\/Plugin.php(337): Sabre\\CalDAV\\Schedule\\Plugin->processICalendarChange()\n#12 \/var\/www\/owncloud\/lib\/composer\/sabre\/event\/lib\/WildcardEmitterTrait.php(89): Sabre\\CalDAV\\Schedule\\Plugin->calendarObjectChange()\n#13 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Plugin.php(897): Sabre\\DAV\\Server->emit()\n#14 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/CalDAV\/Plugin.php(766): Sabre\\CalDAV\\Plugin->validateICalendar()\n#15 \/var\/www\/owncloud\/lib\/composer\/sabre\/event\/lib\/WildcardEmitterTrait.php(89): Sabre\\CalDAV\\Plugin->beforeCreateFile()\n#16 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/Server.php(1094): Sabre\\DAV\\Server->emit()\n#17 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/CorePlugin.php(504): Sabre\\DAV\\Server->createFile()\n#18 \/var\/www\/owncloud\/lib\/composer\/sabre\/event\/lib\/WildcardEmitterTrait.php(89): Sabre\\DAV\\CorePlugin->httpPut()\n#19 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/Server.php(472): Sabre\\DAV\\Server->emit()\n#20 \/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAV\/Server.php(253): Sabre\\DAV\\Server->invokeMethod()\n#21 \/var\/www\/owncloud\/apps\/dav\/lib\/Server.php(345): Sabre\\DAV\\Server->start()\n#22 \/var\/www\/owncloud\/apps\/dav\/appinfo\/v2\/remote.php(31): OCA\\DAV\\Server->exec()\n#23 \/var\/www\/owncloud\/remote.php(165): require_once(’\/var\/www\/ownclo…’)\n#24 {main}",“File”:"\/var\/www\/owncloud\/lib\/composer\/sabre\/dav\/lib\/DAVACL\/AbstractPrincipalCollection.php",“Line”:116}"}

also, we find this strange error message in the log, which keeps repeating:

“reqId”:“Qzaq8SHnnObPi0C3I2yY”,“level”:0,“time”:“2022-03-21T20:28:38+00:00”,“remoteAddr”:“x.x.x.x”,“user”:"–",“app”:“OC\User\Session::validateToken”,“method”:“REPORT”,“url”:"/remote.php/dav/calendars/John%20Doe/",“message”:“token b69621d29a35fad546da6c255fceb0d1e105d75360c1f131d1991836f799efba2181b294552a641b7482100717b15db1bfca71e398b33b8b0962a67594dcd8c4, not found”

thanks!!

Irrelevant. The OP didn’t mention the use of outlook.