[Bug]: Not possible to delete a remnant if no active LDAP configuration are present

⚠️ 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

The directory server of our organization has let's say disappeared. We continued to use the Nextcloud instance but with the built-in user backend.

We now still see account remnants of the disappeared directory in terms of rows in the oc_accounts table as well as user directories in the data directory.

We also see entries in the log where it says "User 042E7FA3-6B7D-45BD-A764-197079C316C9 still has unscanned files after running background scan, background scan might be stopped prematurely"

I tried occ user:sync-account-data but without success. Also occ user:list does not show the remnants.

Is there a safe, manual way to get rid of these remnants?

Steps to reproduce

1. Set up Nextcloud with a functioning LDAP user backend connected to a directory and user from there.
2. Kill down the LDAP directory.
3. Disable the LDAP user backend.
4. Create new users in the default database backend.

Expected behavior

Users/accounts from the directory should be purged. At least occ user:sync-account-data command should notice and purge the accounts.

Installation method

Community Manual installation with Archive

Nextcloud Server version

27

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Nginx

Database engine version

MariaDB

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": {
        "debug": false,
        "loglevel": 2,
        "log_rotate_size": 104857600,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***",
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "27.1.7.2",
        "overwriteprotocol": "https",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",,
        "ldapIgnoreNamingRules": false,
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "maintenance": false,
        "filelocking.enabled": true,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "dbindex": 0,
            "timeout": 1.5
        },
        "theme": "",
        "default_phone_region": "GB",
        "app_install_overwrite": [
            "spreed",
            "calendar",
            "jitsi"
        ],
        "updater.release.channel": "stable",
        "preview_max_memory": 512,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpsecure": "tls"
    }
}

List of activated Apps

Enabled:
  - activity: 2.19.0
  - announcementcenter: 6.8.0
  - bruteforcesettings: 2.7.0
  - calendar: 4.6.6
  - calendar_resource_management: 0.6.0
  - circles: 27.0.1
  - cloud_federation_api: 1.10.0
  - collectives: 2.10.0
  - comments: 1.17.0
  - contacts: 5.5.3
  - contactsinteraction: 1.8.0
  - dashboard: 7.7.0
  - dav: 1.27.0
  - deck: 1.11.4
  - federatedfilesharing: 1.17.0
  - federation: 1.17.0
  - files: 1.22.0
  - files_accesscontrol: 1.17.1
  - files_automatedtagging: 1.17.0
  - files_external: 1.19.0
  - files_pdfviewer: 2.8.0
  - files_reminders: 1.0.0
  - files_retention: 1.16.0
  - files_rightclick: 1.6.0
  - files_sharing: 1.19.0
  - files_trashbin: 1.17.0
  - files_versions: 1.20.0
  - firstrunwizard: 2.16.0
  - forms: 3.4.6
  - groupfolders: 15.3.5
  - integration_gitlab: 1.0.19
  - integration_openproject: 2.6.1
  - jitsi: 0.18.0
  - logreader: 2.12.0
  - lookup_server_connector: 1.15.0
  - mail: 3.5.7
  - nextcloud_announcements: 1.16.0
  - notes: 4.9.2
  - notifications: 2.15.0
  - oauth2: 1.15.2
  - onlyoffice: 8.2.4
  - password_policy: 1.17.0
  - passwords: 2023.12.32
  - polls: 5.4.3
  - privacy: 1.11.0
  - provisioning_api: 1.17.0
  - recommendations: 1.6.0
  - related_resources: 1.2.0
  - serverinfo: 1.17.0
  - settings: 1.9.0
  - sharebymail: 1.17.0
  - spreed: 17.1.6
  - support: 1.10.0
  - survey_client: 1.15.0
  - systemtags: 1.17.0
  - tasks: 0.15.0
  - text: 3.8.0
  - theming: 2.2.0
  - twofactor_backupcodes: 1.16.0
  - updatenotification: 1.17.0
  - user_status: 1.7.0
  - viewer: 2.1.0
  - weather_status: 1.7.0
  - workflowengine: 2.9.0
Disabled:
  - admin_audit: 1.17.0
  - encryption: 2.15.0
  - photos: 2.3.0 (installed 1.2.3)
  - suspicious_login: 5.0.0
  - twofactor_totp: 9.0.0
  - user_ldap: 1.17.0 (installed 1.14.1)

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

No response

Additional info

No response