[Bug]: unserialize(): Error at offset 61 of 64 bytes at CustomPropertiesBackend.php#564

⚠️ 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've checked my Nextcloud logs and there afe > 27,000 error messages like this:

unserialize(): Error at offset 61 of 64 bytes at /var/www/nextcloud/apps/dav/lib/DAV/CustomPropertiesBackend.php#564 

The error message occurs multiple times a minute. I can see a pattern: Most of the time it occurs at either half a minute or at the full minute. Unfortunately I cannot tell the origin of the message / bug-affected module. All I have is the error message.

Steps to reproduce

(not sure how to reproduce the issue, since I cannot tell the origin).

Expected behavior

I expect to have no error message like this, esp not at that frequency (twice or more per minute).

Nextcloud Server version

30

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.2

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

{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "cloud.mydomain.tld",
            "localhost"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "overwrite.cli.url": "https:\/\/cloud.mydomain.tld",
        "dbtype": "pgsql",
        "version": "30.0.5.1",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "logtimezone": "UTC",
        "log_type": "file",
        "logfile": "\/var\/log\/nextcloud.log",
        "loglevel": 3,
        "installed": true,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "theme": "",
        "trashbin_retention_obligation": "30",
        "htaccess.RewriteBase": "\/",
        "asset-pipeline.enabled": true,
        "activity_expire_days": 30,
        "mail_smtpsecure": "tls",
        "mail_smtpauthtype": "PLAIN",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 6379,
            "timeout": 0
        },
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "forwarded_for_headers": [
            "HTTP_X_FORWARDED_FOR"
        ],
        "share_folder": "\/Von anderen geteilt\/",
        "default_phone_region": "DE",
        "maintenance_window_start": 1,
        "memories.exiftool": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/exiftool-amd64-glibc",
        "memories.vod.path": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/go-vod-amd64",
        "enabledPreviewProviders": [
            "OC\\Preview\\HEIC",
            "OC\\Preview\\TIFF",
            "OC\\Preview\\Movie",
            "OC\\Preview\\Image"
        ],
        "preview_max_x": 1024,
        "preview_max_y": 1024,
        "preview_max_memory": 2048,
        "preview_max_filesize_image": 150,
        "memories.vod.disable": false,
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe"
    }
}

List of activated Apps

Enabled:
  - admin_audit: 1.20.0
  - app_api: 4.0.5
  - calendar: 5.0.9
  - cloud_federation_api: 1.13.0
  - comments: 1.20.1
  - contacts: 6.1.3
  - contactsinteraction: 1.11.0
  - dav: 1.31.1
  - deck: 1.14.3
  - federatedfilesharing: 1.20.0
  - files: 2.2.0
  - files_pdfviewer: 3.0.0
  - files_sharing: 1.22.0
  - files_trashbin: 1.20.1
  - files_versions: 1.23.0
  - firstrunwizard: 3.0.0
  - logreader: 3.0.0
  - lookup_server_connector: 1.18.0
  - notes: 4.11.0
  - notifications: 3.0.0
  - notify_push: 1.0.0
  - oauth2: 1.18.1
  - photos: 3.0.2
  - privacy: 2.0.0
  - provisioning_api: 1.20.0
  - quota_warning: 1.20.0
  - serverinfo: 2.0.0
  - settings: 1.13.0
  - tasks: 0.16.1
  - text: 4.1.0
  - theming: 2.5.0
  - twofactor_backupcodes: 1.19.0
  - twofactor_webauthn: 2.1.0
  - 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)
  - bruteforcesettings: 3.0.0 (installed 1.0.2)
  - circles: 30.0.0 (installed 0.20.7)
  - dashboard: 7.10.0 (installed 4.0.6)
  - encryption: 2.18.0 (installed 1.0.0)
  - federation: 1.20.0 (installed 1.19.0)
  - files_downloadlimit: 3.0.0 (installed 2.0.0)
  - files_external: 1.22.0 (installed 1.1.2)
  - files_markdown: 2.4.1 (installed 2.4.1)
  - files_reminders: 1.3.0 (installed 1.2.0)
  - files_rightclick: 0.15.1 (installed 1.6.0)
  - maps: 1.5.0 (installed 1.5.0)
  - nextcloud_announcements: 2.0.0 (installed 1.18.0)
  - password_policy: 2.0.0 (installed 1.2.2)
  - recommendations: 3.0.0 (installed 2.1.0)
  - related_resources: 1.5.0 (installed 1.4.0)
  - sharebymail: 1.20.0 (installed 1.19.0)
  - support: 2.0.0 (installed 1.2.1)
  - survey_client: 2.0.0 (installed 1.17.0)
  - suspicious_login: 8.0.0
  - systemtags: 1.20.0 (installed 1.19.0)
  - twofactor_nextcloud_notification: 4.0.0
  - twofactor_totp: 12.0.0-dev (installed 1.3.1)
  - 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

No errors have been found.

Nextcloud Logs

unserialize(): Error at offset 61 of 64 bytes at /var/www/nextcloud/apps/dav/lib/DAV/CustomPropertiesBackend.php#564

Additional info

No response

Start at apps/dav/lib/DAV/CustomPropertiesBackend.php line 564 and trace the custom-property value being unserialized. Use the reported Nextcloud 30 and PHP 8.2 context to investigate the offset-61-of-64 error; done means identifying why the malformed value is encountered and preventing the repeated log error.