Access to shared calendar not working anymore

[arno1979]

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Steps to reproduce

1. Create a guest user by sharing a folder
2. Allow access to calendar app for guest users
3. Activate the guest account, set a password
4. Share an existing calendar with the new guest user, give editing permission
5. Login with the guest user

Expected behaviour

After the login the shared calendar should be visible

Actual behaviour

Login works but the shared calendar is not being displayed. In the left hand panel the loading icon keeps circling, never finishing the process.
In the log I can see the following message, I especially noticed the message "Principal with name guest_app not found"

{"reqId":"p3kXPnynVBujguKjxlnQ","level":0,"time":"2025-07-21T07:56:42+00:00","remoteAddr":"xxx.xxx.xxx.xxx","user":"user@domain.tld","app":"webdav","method":"PROPFIND","url":"/remote.php/dav/principals/users/user@domain.tld/","message":"Principal with name guest_app not found","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36","version":"31.0.7.1","exception":{"Exception":"Sabre\\DAV\\Exception\\NotFound","Message":"Principal with name guest_app not found","Code":0,"Trace":[{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Tree.php","line":95,"function":"getChild","class":"Sabre\\DAVACL\\AbstractPrincipalCollection","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/Plugin.php","line":335,"function":"getNodeForPath","class":"Sabre\\DAV\\Tree","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/Plugin.php","line":388,"function":"getPrincipalMembership","class":"Sabre\\DAVACL\\Plugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/Plugin.php","line":641,"function":"principalMatchesPrincipal","class":"Sabre\\DAVACL\\Plugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/Plugin.php","line":199,"function":"getCurrentUserPrivilegeSet","class":"Sabre\\DAVACL\\Plugin","type":"->"},{"file":"domain.tld/apps/dav/lib/Connector/Sabre/DavAclPlugin.php","line":36,"function":"checkPrivileges","class":"Sabre\\DAVACL\\Plugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/Plugin.php","line":936,"function":"checkPrivileges","class":"OCA\\DAV\\Connector\\Sabre\\DavAclPlugin","type":"->"},{"file":"domain.tld/apps/dav/lib/Connector/Sabre/DavAclPlugin.php","line":89,"function":"propFind","class":"Sabre\\DAVACL\\Plugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"propFind","class":"OCA\\DAV\\Connector\\Sabre\\DavAclPlugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Server.php","line":1052,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Server.php","line":984,"function":"getPropertiesByNode","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Server.php","line":1664,"function":"getPropertiesIteratorForPath","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Server.php","line":1649,"function":"writeMultiStatus","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":346,"function":"generateMultiStatus","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpPropFind","class":"Sabre\\DAV\\CorePlugin","type":"->"},{"file":"domain.tld/3rdparty/sabre/dav/lib/DAV/Server.php","line":472,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/apps/dav/lib/Connector/Sabre/Server.php","line":49,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"domain.tld/apps/dav/lib/Server.php","line":401,"function":"start","class":"OCA\\DAV\\Connector\\Sabre\\Server","type":"->"},{"file":"domain.tld/apps/dav/appinfo/v2/remote.php","line":21,"function":"exec","class":"OCA\\DAV\\Server","type":"->"},{"file":"/remote.php","line":145,"args":["domain.tld/apps/dav/appinfo/v2/remote.php"],"function":"require_once"}],"File":"domain.tld/3rdparty/sabre/dav/lib/DAVACL/AbstractPrincipalCollection.php","Line":116,"message":"Principal with name guest_app not found","exception":{},"CustomMessage":"Principal with name guest_app not found"}}

Server configuration

Web server: Apache

Database: Maria

PHP version: 8.2

Nextcloud version: 31.0.7

- activity: 4.0.0 - app_api: 5.0.2 - bruteforcesettings: 4.0.0 - calendar: 5.3.6 - circles: 31.0.0 - cloud_federation_api: 1.14.0 - collectives: 3.0.2 - comments: 1.21.0 - contacts: 7.2.0 - dashboard: 7.11.0 - dav: 1.33.0 - federatedfilesharing: 1.21.0 - federation: 1.21.0 - files: 2.3.1 - files_downloadlimit: 4.0.0 - files_pdfviewer: 4.0.0 - files_reminders: 1.4.0 - files_sharing: 1.23.1 - files_trashbin: 1.21.0 - files_versions: 1.24.0 - firstrunwizard: 4.0.0 - guests: 4.3.0 - logreader: 4.0.0 - lookup_server_connector: 1.19.0 - nextcloud_announcements: 3.0.0 - notifications: 4.0.0 - oauth2: 1.19.1 - password_policy: 3.0.0 - privacy: 3.0.0 - profile: 1.0.0 - provisioning_api: 1.21.0 - recommendations: 4.0.0 - related_resources: 2.0.0 - serverinfo: 3.0.0 - settings: 1.14.0 - sharebymail: 1.21.0 - support: 3.0.0 - survey_client: 3.0.0 - systemtags: 1.21.1 - text: 5.0.0 - theming: 2.6.1 - twofactor_backupcodes: 1.20.0 - updatenotification: 1.21.0 - user_status: 1.11.0 - viewer: 4.0.0 - weather_status: 1.11.0 - webhook_listeners: 1.2.0 - workflowengine: 2.13.0 -

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder

{ "system": { "instanceid": "***REMOVED SENSITIVE VALUE***", "passwordsalt": "***REMOVED SENSITIVE VALUE***", "secret": "***REMOVED SENSITIVE VALUE***", "trusted_domains": [ "cloud.berliner-museumsverband.de" ], "datadirectory": "***REMOVED SENSITIVE VALUE***", "dbtype": "mysql", "version": "31.0.7.1", "dbname": "***REMOVED SENSITIVE VALUE***", "dbhost": "***REMOVED SENSITIVE VALUE***", "dbport": "", "dbtableprefix": "oc_", "mysql.utf8mb4": true, "dbuser": "***REMOVED SENSITIVE VALUE***", "dbpassword": "***REMOVED SENSITIVE VALUE***", "installed": true, "default_phone_region": "DE", "defaultapp": "calendar", "mail_from_address": "***REMOVED SENSITIVE VALUE***", "mail_smtpmode": "sendmail", "mail_sendmailmode": "smtp", "mail_domain": "***REMOVED SENSITIVE VALUE***", "memcache.local": "\\OC\\Memcache\\APCu", "memcache.locking": "\\OC\\Memcache\\Redis", "redis": { "host": "***REMOVED SENSITIVE VALUE***", "port": "6379", "timeout": 0, "password": "***REMOVED SENSITIVE VALUE***" }, "maintenance": false, "theme": "", "loglevel": 0, "logfile": "\/var\/log\/nextcloud\/nextcloud.log", "log_rotate_size": 104857600, "mail_smtpport": "587", "mail_smtpauth": true, "mail_smtpname": "***REMOVED SENSITIVE VALUE***", "mail_smtppassword": "***REMOVED SENSITIVE VALUE***", "maintenance_window_start": 1, "mail_smtphost": "***REMOVED SENSITIVE VALUE***", "app_install_overwrite": [ "integration_ews" ], "overwrite.cli.url": "https:\/\/cloud.berliner-museumsverband.de\/", "simpleSignUpLink.shown": false, "auth.bruteforce.protection.enabled": false } }

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

Browser

Browser name: Chrome

Browser version: 137.0.7151.104

Operating system: Windows

[kesselb]

Thanks for reaching out 👍

We will address that problem with the August maintenance release.

Please don't hesitate to try the patch nextcloud/server#54167 (it's a rather small change).