[Bug]: NotImplementedException is thrown when I try to access calDav Calendars

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

After updating to either 29 or 30, I can't sync calendars with new devices. In Dav5X I can connect to the server and the contact tab is populated, but the calendars stay empty (see the attached log).

When I try to query the calendars via curl, the initial list work, but querying calendar items leads to the NotImplemented error (see curl.txt)

The .well-known addresses for cal and carddav (e.g. https://cloud.domain.de/.well-known/caldav) are redirected to https://cloud.domain.de/remote.php/dav/

My traefik config for calDav, which has worked for years:

  - traefik.http.middlewares.nextcloud_redirect.redirectregex.permanent=true
  - traefik.http.middlewares.nextcloud_redirect.redirectregex.regex=/.well-known/(card|cal)dav
  - traefik.http.middlewares.nextcloud_redirect.redirectregex.replacement=/remote.php/dav/

But I also tried:

  - traefik.http.middlewares.nextcloud_redirectregex.redirectregex.permanent=true
  - traefik.http.middlewares.nextcloud_redirectregex.redirectregex.regex='https://(.*)/.well-known/(?:card|cal)dav/'
  - traefik.http.middlewares.nextcloud_redirectregex.redirectregex.replacement='https://$${1}/remote.php/dav/'

Steps to reproduce

1. Updating to v29 or 30 I guess

Expected behavior

Calendars can be synced with new clients

Nextcloud Server version

30

Operating system

Debian/Ubuntu

PHP engine version

8.3

Web server

NginX (Behind Traefik3)

Database engine version

Postgres

Is this bug present after an update or on a fresh install?

Upgraded to a Major version (ex 28 to 29)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

    "system": {
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "apps_paths": [
            {
                "path": "\/nextcloud\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/nextcloud\/apps2",
                "url": "\/apps2",
                "writable": true
            }
        ],
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "cloud.domain.de"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "onlyoffice": {
            "jwt_secret": "***REMOVED SENSITIVE VALUE***",
            "jwt_header": "Authorization"
        },
        "maintenance_window_start": 1,
        "overwrite.cli.url": "https:\/\/cloud.maggiwuerze.de",
        "overwriteprotocol": "https",
        "dbtype": "pgsql",
        "version": "30.0.4.1",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "logtimezone": "Etc\/UTC",
        "logdateformat": "Y-m-d H:i:s",
        "maintenance": false,
        "updater.release.channel": "stable",
        "mail_smtpmode": "smtp",
        "mail_smtpauthtype": "LOGIN",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpsecure": "ssl",
        "loglevel": 0,
        "trashbin_retention_obligation": "auto, 30",
        "mail_sendmailmode": "smtp",
        "default_phone_region": "DE"
    }
}

List of activated Apps

  - app_api: 4.0.3
  - calendar: 5.0.8
  - circles: 30.0.0
  - cloud_federation_api: 1.13.0
  - comments: 1.20.1
  - contactsinteraction: 1.11.0
  - dav: 1.31.1
  - dav_push: 0.0.1
  - drawio: 3.0.3
  - federatedfilesharing: 1.20.0
  - federation: 1.20.0
  - files: 2.2.0
  - files_3dmodelviewer: 0.0.14
  - files_downloadlimit: 3.0.0
  - files_external: 1.22.0
  - files_pdfviewer: 3.0.0
  - files_reminders: 1.3.0
  - files_sharing: 1.22.0
  - files_trashbin: 1.20.1
  - files_versions: 1.23.0
  - forms: 4.3.4
  - logreader: 3.0.0
  - lookup_server_connector: 1.18.0
  - nextcloud_announcements: 2.0.0
  - notifications: 3.0.0
  - oauth2: 1.18.1
  - onlyoffice: 9.5.0
  - password_policy: 2.0.0
  - privacy: 2.0.0
  - provisioning_api: 1.20.0
  - recommendations: 3.0.0
  - related_resources: 1.5.0
  - serverinfo: 2.0.0
  - settings: 1.13.0
  - sharebymail: 1.20.0
  - support: 2.0.0
  - survey_client: 2.0.0
  - systemtags: 1.20.0
  - tasks: 0.16.1
  - text: 4.1.0
  - theming: 2.5.0
  - twofactor_backupcodes: 1.19.0
  - twofactor_totp: 12.0.0-dev
  - updatenotification: 1.20.0
  - viewer: 3.0.0
  - webhook_listeners: 1.1.0-dev
  - workflowengine: 2.12.0
Disabled:
  - activity: 3.0.0 (installed 2.21.1)
  - admin_audit: 1.20.0
  - analytics: 5.2.0 (installed 5.2.0)
  - audioplayer: 3.4.1 (installed 3.4.1)
  - breezedark: 29.0.0 (installed 29.0.0)
  - bruteforcesettings: 3.0.0 (installed 2.2.0)
  - dashboard: 7.10.0 (installed 7.0.0)
  - encryption: 2.18.0
  - extract: 1.3.6 (installed 1.3.6)
  - files_3d: 0.5.0 (installed 0.5.0)
  - files_clipboard: 0.7.1 (installed 0.7.1)
  - files_rightclick: 0.15.1 (installed 1.6.0)
  - firstrunwizard: 3.0.0 (installed 2.1)
  - flowupload: 1.1.3 (installed 1.1.3)
  - google_synchronization: 3.0.0 (installed 3.0.0)
  - mail: 4.1.0 (installed 4.1.0)
  - metadata: 0.21.0 (installed 0.21.0)
  - news: 25.1.1 (installed 25.1.1)
  - notes: 4.11.0 (installed 4.11.0)
  - photos: 3.0.2 (installed 2.5.0)
  - richdocuments: 8.5.3 (installed 8.5.3)
  - richdocumentscode: 24.4.1002 (installed 24.4.1002)
  - spreed: 20.1.1 (installed 20.1.1)
  - suspicious_login: 8.0.0
  - twofactor_nextcloud_notification: 4.0.0
  - unsplash: 3.0.3 (installed 3.0.3)
  - user_ldap: 1.21.0
  - user_status: 1.10.0 (installed 1.0.1)
  - weather_status: 1.10.0 (installed 1.0.0)

Nextcloud Signing status

Nextcloud Logs

Exception thrown: Sabre\DAV\Exception\NotImplemented 

ArgumentCountError next() expects exactly 1 argument, 0 given

StackTrace from the NotImplementedException:

see stack.txt

Additional info

curl.txt
davx5-log.txt
stack.txt

Start by reviewing stack.txt alongside curl.txt and davx5-log.txt, then reproduce the failing calendar-item request against /remote.php/dav. Trace the Sabre\DAV\Exception\NotImplemented and ArgumentCountError shown in the logs. Done means calendar item queries complete successfully and new clients can synchronize calendars.