[Bug]: Birthday calendar shows events for deleted contacts

⚠️ 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

I have (at least one) event on my birthday calendar for a contact that has been deleted for a while. I've double check, the contact was deleted. I've found no occurrence for this contact everywhere in my Nextcloud.

My Nextcloud is self hosted in version 31.0.8. Calendar app is V5.5.2. I've performed ./occ dav:sync-birthday-calendar for my user without success.

Steps to reproduce

1. Create a contact with a birthday date
2. Check the birthday calendar to preview the event related to this contact
3. Delete the contact created in 1.
4. The event for the birthday of this contact is still here

Expected behavior

Event for deleted contact should be removed from the birthday agenda.

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

MySQL

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

None

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

www-data@nextcloud:~/nextcloud$ ./occ config:list system
{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": {
            "1": "192.168.1.33",
            "2": "nextcloud",
            "3": "cloud.rps.ovh",
            "4": "10.1.0.1",
            "5": "192.168.1.35",
            "6": "uno",
            "7": "rps.ovh",
            "8": "nextcloud.lan"
        },
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "31.0.8.1",
        "overwrite.cli.url": "https:\/\/cloud.rps.ovh",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "enable_previews": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\PNG",
            "OC\\Preview\\JPEG",
            "OC\\Preview\\GIF",
            "OC\\Preview\\BMP",
            "OC\\Preview\\XBitmap",
            "OC\\Preview\\MP3",
            "OC\\Preview\\TXT",
            "OC\\Preview\\MarkDown",
            "OC\\Preview\\MSOffice2003",
            "OC\\Preview\\MSOffice2007",
            "OC\\Preview\\MSOfficeDoc",
            "OC\\Preview\\OpenDocument",
            "OC\\Preview\\PDF",
            "OC\\Preview\\TIFF",
            "OC\\Preview\\Movie",
            "OC\\Preview\\HEIC",
            "OC\\Preview\\Image"
        ],
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpsecure": "ssl",
        "maintenance": false,
        "maintenance_window_start": 1,
        "theme": "",
        "has_rebuilt_cache": true,
        "updater.release.channel": "stable",
        "app_install_overwrite": {
            "0": "occweb",
            "1": "spreed",
            "2": "files_reader",
            "3": "admin_notifications",
            "4": "end_to_end_encryption",
            "5": "folderplayer",
            "6": "files_clipboard",
            "7": "activitylog",
            "8": "workin2gether",
            "9": "passman",
            "10": "cospend",
            "11": "quickaccesssorting",
            "12": "printer",
            "13": "uploaddetails",
            "14": "mindmap_app",
            "15": "files_external_dropbox",
            "16": "joplin",
            "17": "dicomviewer",
            "18": "ocsms",
            "19": "emlviewer",
            "20": "gpxedit",
            "21": "sharerenamer",
            "22": "workflow_pdf_converter",
            "23": "passwords",
            "24": "transmission",
            "26": "socialsharing_email",
            "27": "scanner",
            "28": "gpxmotion",
            "29": "documentserver_community",
            "30": "group_everyone",
            "31": "bookmarks_fulltextsearch",
            "33": "afterlogic",
            "34": "fulltextsearch",
            "35": "apporder",
            "36": "fulltextsearch_elasticsearch",
            "37": "files_fulltextsearch",
            "38": "files_markdown",
            "39": "breezedark",
            "40": "ocdownloader",
            "41": "extract",
            "42": "flowupload",
            "43": "transfer",
            "44": "customproperties",
            "45": "epubreader",
            "46": "ransomware_protection",
            "47": "files_downloadactivity",
            "48": "mail_roundcube",
            "49": "memories",
            "50": "hedgenext",
            "51": "metadata",
            "52": "news",
            "53": "files_archive",
            "54": "checksum",
            "55": "workflow_kitinerary",
            "56": "files_retention",
            "57": "holiday_calendars",
            "58": "twainwebscan",
            "59": "integration_whiteboard",
            "60": "files_trackdownloads",
            "61": "hibp",
            "62": "hibp_login_check",
            "63": "gluusso",
            "64": "orcid",
            "65": "otpmanager",
            "66": "files_scripts",
            "67": "files_staticmimecontrol",
            "69": "files_automatedtagging",
            "70": "maps",
            "71": "integration_collaboard",
            "72": "globalsiteselector"
        },
        "preview_libreoffice_path": "\/usr\/bin\/soffice",
        "onlyoffice": {
            "verify_peer_off": true
        },
        "encryption.legacy_format_support": false,
        "encryption.key_storage_migrated": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "forwarded-for-headers": [
            "X-Forwarded-For",
            "HTTP_X_FORWARDED_FOR"
        ],
        "default_phone_region": "FR",
        "preview_max_memory": 4096,
        "preview_max_filesize_image": 50,
        "preview_max_x": 1024,
        "preview_max_y": 1024,
        "jpeg_quality": 80,
        "trashbin_retention_obligation": "30, 60",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "loglevel": 3,
        "log_type": "file",
        "logfile": "\/var\/log\/nextcloud\/nextcloud.log",
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "memories.exiftool": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/exiftool-amd64-glibc",
        "mail_smtpauthtype": "LOGIN",
        "htaccess.RewriteBase": "\/nextcloud",
        "memories.ffmpeg_path": "\/usr\/bin\/ffmpeg",
        "memories.ffprobe_path": "\/usr\/bin\/ffprobe",
        "memories.transcoder": "\/var\/www\/nextcloud\/apps\/memories\/exiftool-bin\/go-vod-amd64",
        "memories.no_transcode": false,
        "memories.qsv": false,
        "memories.vod.path": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/go-vod-amd64",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "filelocking.enabled": true,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "dbindex": 0,
            "timeout": 1.5
        },
        "data-fingerprint": "2ef849be57025e5a6b18264bb526a5d2",
        "allow_local_address": true,
        "memories.db.triggers.fcu": true,
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "memories.gis_type": 1,
        "defaultapp": "dashboard,files",
        "activity_expire_days": 90,
        "memories.vod.disable": false
    }
}

List of activated Apps

www-data@nextcloud:~/nextcloud$ ./occ app:list
Enabled:
  - activity: 4.0.0
  - admin_audit: 1.21.0
  - app_api: 5.0.2
  - bookmarks: 15.2.0
  - bruteforcesettings: 4.0.0
  - calendar: 5.5.2
  - camerarawpreviews: 0.8.7
  - checksum: 1.2.6
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - contacts: 7.2.6
  - contactsinteraction: 1.12.0
  - cookbook: 0.11.3
  - dav: 1.33.0
  - drawio: 3.1.0
  - duplicatefinder: 1.7.3
  - event_update_notification: 2.6.1
  - extract: 1.3.6
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadactivity: 1.18.1
  - files_downloadlimit: 4.0.0
  - files_external: 1.23.0
  - files_fulltextsearch: 31.0.0
  - files_mindmap: 0.0.33
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_retention: 2.0.1
  - files_scripts: 4.1.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - firstrunwizard: 4.0.0
  - forms: 5.1.2
  - fulltextsearch: 31.0.0
  - fulltextsearch_elasticsearch: 31.0.0
  - google_synchronization: 4.0.1
  - gpxpod: 7.0.4
  - integration_google: 4.1.0
  - integration_mastodon: 3.2.1
  - integration_openstreetmap: 2.1.0
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - maps: 1.6.0
  - memories: 7.6.2
  - metadata: 0.22.0
  - notes: 4.12.3
  - notifications: 4.0.0
  - oauth2: 1.19.1
  - occweb: 0.2.3
  - ownershiptransfer: 1.2.1
  - password_policy: 3.0.0
  - passwords: 2025.7.20
  - photos: 4.0.0
  - polls: 8.4.3
  - previewgenerator: 5.9.0
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - quickaccesssorting: 3.0.0
  - quota_warning: 1.21.0
  - ransomware_protection: 1.14.0
  - recognize: 9.0.7
  - related_resources: 2.0.0
  - richdocuments: 8.7.4
  - richdocumentscode: 25.4.403
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - side_menu: 5.1.1
  - support: 3.0.0
  - survey_client: 3.0.0
  - suspicious_login: 9.0.1
  - systemtags: 1.21.1
  - tasks: 0.16.1
  - text: 5.0.0
  - theming: 2.6.1
  - transfer: 0.6.3
  - twofactor_backupcodes: 1.20.0
  - updatenotification: 1.21.0
  - user_ldap: 1.22.0
  - viewer: 4.0.0
  - webhook_listeners: 1.2.0
  - workflowengine: 2.13.0
Disabled:
  - comments: 1.21.0 (installed 1.13.0)
  - dashboard: 7.11.0 (installed 7.8.0)
  - documentserver_community: 0.2.0 (installed 0.2.0)
  - encryption: 2.19.0 (installed 2.13.0)
  - files_archive: 1.2.7 (installed 1.2.7)
  - files_automatedtagging: 2.0.0 (installed 2.0.0)
  - files_versions: 1.24.0 (installed 1.24.0)
  - guests: 4.5.0 (installed 4.5.0)
  - hedgenext: 0.0.15 (installed 0.0.15)
  - holiday_calendars: 0.3.0 (installed 0.3.0)
  - nextcloud_announcements: 3.0.0 (installed 1.12.0)
  - recommendations: 4.0.0 (installed 1.2.0)
  - twofactor_nextcloud_notification: 5.0.0
  - twofactor_totp: 13.0.0-dev.0
  - user_status: 1.11.0 (installed 1.2.0)
  - weather_status: 1.11.0 (installed 1.8.0)
  - whiteboard: 1.1.3 (installed 1.1.3)
  - workflow_script: 2.0.0 (installed 2.0.0)

Nextcloud Signing status

Technical information
=====================
The following list covers which files have failed the integrity check. Please read
the previous linked documentation to learn more about the errors and how to fix
them.

Results
=======
- files_mindmap
	- EXCEPTION
		- OC\IntegrityCheck\Exceptions\InvalidSignatureException
		- Certificate is not valid.

Raw output
==========
Array
(
    [files_mindmap] => Array
        (
            [EXCEPTION] => Array
                (
                    [class] => OC\IntegrityCheck\Exceptions\InvalidSignatureException
                    [message] => Certificate is not valid.
                )

        )

)

Nextcloud Logs

I have no relevant log about this behavior.

Additional info

My instance is behind a reverse proxy (NGINX) that manage https

Start by reproducing the issue with the reported contact creation and deletion steps, then run ./occ dav:sync-birthday-calendar to compare the result. Trace the birthday calendar behavior after contact deletion; done means the deleted contact's birthday event is removed from the calendar.