[Bug]: `App token login name does not match` error (on Calendar access through MacOS CalendarAgent)

⚠️ 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 (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

I am not sure if this issue relates to the core server or the Calendar app. However, looking at the log file and the "missing app in context", it feels to belong to the core server:

{"reqId":"<randomstring>,"level":3,"time":"2023-04-17T23:25:14+00:00","remoteAddr":"<ip>","user":"--","app":"no app in context","method":"REPORT","url":"/remote.php/dav/principals/users/<user>/","message":"App token login name does not match","userAgent":"macOS/12.6.4 (<removed>) CalendarAgent/961.4.2","version":"26.0.0.11","data":{"tokenLoginName":"<user>","sessionLoginName":"<user_address_mail"},"id":"<id>"}

At least since the latest updates (Calendar 4.3.3 and Nextcloud 26.0.0) I frequently get this error message - for instance if I trigger a manual update from an Apple Calendar client (MacOS 12.6.4).

What else is affected is not clear - there are calendar events visible in that corresponding client.

Steps to reproduce

1. Install Nexcloud, set up user and user calendar
2. On MacOS (12.6.4) go to Calendar > Account, add a new CalDav account using the instructions from https://docs.nextcloud.com/server/latest/user_manual/en/groupware/sync_osx.html.
3. Wait for the next synchronization in the Calendar app or trigger it manually using Cmd+R
4. Watch how the error message above shows up on synchronization

Expected behavior

Flawless synchronization without error messages

Installation method

None

Nextcloud Server version

26

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.0

Web server

Apache (supported)

Database engine version

MariaDB

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

Updated to a major version (ex. 22.2.3 to 23.0.1)

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***",
        "dbtype": "mysql",
        "version": "26.0.0.11",
        "installed": true,
        "loglevel": 2,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "maintenance": false,
        "trusted_domains": [
            "<domain>"
        ],
        "forcessl": true,
        "mail_smtpmode": "smtp",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "forceSSLforSubdomains": true,
        "default_language": "de",
        "check_for_working_htaccess": true,
        "appcodechecker": true,
        "updatechecker": true,
        "has_internet_connection": "true",
        "trashbin_retention_obligation": "auto",
        "check_for_working_webdav": true,
        "check_for_wellknown_setup": true,
        "appstoreenabled": true,
        "upgrade.disable-web": false,
        "updater.server.url": "https:\/\/updates.nextcloud.com\/updater_server\/",
        "memcache.local": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 6379,
            "password": "***REMOVED SENSITIVE VALUE***",
            "timeout": 0
        },
        "overwrite.cli.url": "https:\/\/<cli_url>",
        "htaccess.RewriteBase": "\/",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "updater.release.channel": "stable",
        "mysql.utf8mb4": true,
        "app_install_overwrite": [
            "twofactor_admin",
            "ransomware_protection",
            "issuetemplate"
        ],
        "mail_sendmailmode": "smtp",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "25",
        "encryption.legacy_format_support": false,
        "encryption.key_storage_migrated": false,
        "default_phone_region": "DE",
        "preview_max_x": 1024,
        "preview_max_y": 1024,
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "updater.secret": "***REMOVED SENSITIVE VALUE***"
    }
}

List of activated Apps

Enabled:
  - activity: 2.18.0
  - bruteforcesettings: 2.6.0
  - calendar: 4.3.3
  - circles: 26.0.0
  - cloud_federation_api: 1.9.0
  - comments: 1.16.0
  - contacts: 5.2.0
  - contactsinteraction: 1.7.0
  - cookbook: 0.10.2
  - cospend: 1.5.8
  - dashboard: 7.6.0
  - dav: 1.25.0
  - deck: 1.9.0
  - external: 5.1.0
  - federatedfilesharing: 1.16.0
  - federation: 1.16.0
  - files: 1.21.1
  - files_antivirus: 5.0.0
  - files_external: 1.18.0
  - files_pdfviewer: 2.7.0
  - files_rightclick: 1.5.0
  - files_sharing: 1.18.0
  - files_trashbin: 1.16.0
  - files_versions: 1.19.1
  - firstrunwizard: 2.15.0
  - groupfolders: 14.0.1
  - logreader: 2.11.0
  - lookup_server_connector: 1.14.0
  - notes: 4.7.2
  - notifications: 2.14.0
  - oauth2: 1.14.0
  - password_policy: 1.16.0
  - photos: 2.2.0
  - privacy: 1.10.0
  - provisioning_api: 1.16.0
  - quota_warning: 1.16.0
  - ransomware_protection: 1.14.0
  - recommendations: 1.5.0
  - related_resources: 1.1.0-alpha1
  - richdocuments: 8.0.1
  - richdocumentscode: 22.5.1301
  - serverinfo: 1.16.0
  - settings: 1.8.0
  - sharebymail: 1.16.0
  - spreed: 16.0.2
  - support: 1.9.0
  - systemtags: 1.16.0
  - tasks: 0.14.5
  - terms_of_service: 2.1.0
  - text: 3.7.2
  - theming: 2.1.1
  - twofactor_admin: 4.1.9
  - twofactor_backupcodes: 1.15.0
  - twofactor_nextcloud_notification: 3.6.0
  - twofactor_totp: 8.0.0-alpha.0
  - updatenotification: 1.16.0
  - user_status: 1.6.0
  - viewer: 1.10.0
  - weather_status: 1.6.0
  - workflowengine: 2.8.0
Disabled:
  - admin_audit: 1.16.0
  - announcementcenter: 6.5.1 (installed 6.5.1)
  - audioplayer: 3.3.1 (installed 3.3.1)
  - camerarawpreviews: 0.8.1 (installed 0.8.1)
  - checksum: 1.2.1 (installed 1.2.1)
  - documentserver_community: 0.1.13 (installed 0.1.13)
  - encryption: 2.14.0 (installed 2.8.1)
  - end_to_end_encryption: 1.12.4 (installed 1.12.4)
  - files_accesscontrol: 1.16.0 (installed 1.16.0)
  - files_markdown: 2.3.6 (installed 2.3.6)
  - forms: 3.2.0 (installed 3.2.0)
  - issuetemplate: 0.7.0 (installed 0.7.0)
  - maps: 1.0.2 (installed 1.0.2)
  - nextcloud_announcements: 1.15.0 (installed 1.9.0)
  - onlyoffice: 7.8.0 (installed 7.8.0)
  - piwik: 0.11.1 (installed 0.11.1)
  - polls: 5.0.0 (installed 5.0.0)
  - shorten: 0.0.15 (installed 0.0.15)
  - socialsharing_email: 2.5.0 (installed 2.5.0)
  - survey_client: 1.14.0 (installed 0.1.5)
  - suspicious_login: 4.4.0
  - unsplash: 2.2.0 (installed 2.2.0)
  - user_ldap: 1.16.0

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

No source file, test, or entry point is named. Reproduce the REPORT request with macOS CalendarAgent and inspect the logged tokenLoginName and sessionLoginName values, then trace whether the mismatch belongs to the core server or Calendar app. Done means synchronization completes without this error message.