[Bug]: Shares become invalid when the SMB username casing changes, creating a different external-storage ID

[FuxPCN]

⚠️ This issue respects the following points: ⚠️

• This is not a troubleshooting question, general support matter, or webserver/proxy problem, but likely a bug (if unsure, ask the Community Help Forum).
• This issue is not already reported on Github OR solved at the Community Help Forum (I've searched!).
• I'm using a maintained major version of Nextcloud Server and tested against the latest patch level. (Supported major versions and current patch levels).
• I agree to follow Nextcloud's Code of Conduct.
• I've tried my best to provide clear reproduction steps that someone unfamiliar with this bug could use to reproduce it.

Bug description

Changing only the capitalization of an SMB username creates a new external-storage ID. Existing shares still reference the old storage and become inaccessible/orphaned.

Steps to reproduce

1. Mount an SMB share using username myuser.
2. Create shares from folders within that mount.
3. Log in again using Myuser.
4. Open the previously shared folders.
5. Shares become inaccessible

Expected behavior

Existing shares remain accessible.

Actual behavior:

The folders appear to exist, but access is denied. Nextcloud reports orphaned shares because they reference the previous storage ID.

Nextcloud Server version

34

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.4

Web server

Apache (supported)

Database engine version

MariaDB

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

Upgraded to a MAJOR version (ex. 31 to 32)

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

sudo -u www-data php occ config:list system
{
    "system": {
        "overwrite.cli.url": "https:\/\/nextcloud.xxx.de\/",
        "htaccess.RewriteBase": "\/",
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "10.10.0.230",
            "localhost",
            "nextcloud.xxx.de",
            "cloud.xxx.de"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "34.0.4.1",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "installed": true,
        "filelocking.enabled": true,
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "timeout": 0
        },
        "maintenance_window_start": 4,
        "twofactor_enforced": "false",
        "twofactor_enforced_groups": [],
        "twofactor_enforced_excluded_groups": [],
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "maintenance": false,
        "default_phone_region": "DE",
        "forbidden_filename_basenames": [
            "con",
            "prn",
            "aux",
            "nul",
            "com0",
            "com1",
            "com2",
            "com3",
            "com4",
            "com5",
            "com6",
            "com7",
            "com8",
            "com9",
            "com\u00b9",
            "com\u00b2",
            "com\u00b3",
            "lpt0",
            "lpt1",
            "lpt2",
            "lpt3",
            "lpt4",
            "lpt5",
            "lpt6",
            "lpt7",
            "lpt8",
            "lpt9",
            "lpt\u00b9",
            "lpt\u00b2",
            "lpt\u00b3"
        ],
        "forbidden_filename_characters": [
            "<",
            ">",
            ":",
            "\"",
            "|",
            "?",
            "*",
            "\\",
            "\/"
        ],
        "forbidden_filename_extensions": [
            " ",
            ".",
            ".filepart",
            ".part"
        ],
        "allow_local_remote_servers": true,
        "internalUsernameAttribute": "sAMAccountName",
        "skeletondirectory": "",
        "theme": "",
        "loglevel": 2,
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "pipe",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "updater.secret": "***REMOVED SENSITIVE VALUE***"
    }
}

List of activated Apps

# sudo -u www-data php occ app:list
Enabled:
  - activity: 7.0.0
  - admin_audit: 1.24.0
  - announcementcenter: 7.5.0
  - app_api: 34.0.0
  - appointments: 2.7.4
  - appstore: 1.0.0
  - bruteforcesettings: 7.0.0
  - calendar: 6.6.1
  - circles: 34.0.0
  - cloud_federation_api: 1.18.0
  - comments: 1.24.0
  - contacts: 8.9.0
  - contactsinteraction: 1.15.0
  - dashboard: 7.14.0
  - dav: 1.40.0
  - deck: 1.18.5
  - federatedfilesharing: 1.24.0
  - federation: 1.24.0
  - files: 2.6.0
  - files_downloadlimit: 5.2.0
  - files_external: 1.26.0
  - files_lock: 34.0.1
  - files_pdfviewer: 7.0.0
  - files_reminders: 1.7.0
  - files_sharing: 1.26.0
  - files_trashbin: 1.24.0
  - files_versions: 1.27.0
  - firstrunwizard: 7.0.0-dev.0
  - forms: 5.4.0
  - impersonate: 5.0.0
  - logreader: 7.0.0
  - lookup_server_connector: 1.22.0
  - mail: 5.12.0
  - mail_roundcube_bridge: 1.2.2
  - nextcloud_announcements: 6.0.0
  - notes: 6.1.0
  - notifications: 7.0.0-dev.1
  - notify_push: 1.4.1
  - oauth2: 1.22.0
  - office: 1.0.0
  - password_policy: 6.0.0-dev.0
  - photos: 7.0.0
  - privacy: 6.0.0-dev.1
  - profile: 1.3.0
  - provisioning_api: 1.24.0
  - recommendations: 7.0.0
  - related_resources: 5.0.0-dev.0
  - richdocuments: 11.1.1
  - richdocumentscode: 26.4.303
  - serverinfo: 6.0.0
  - settings: 1.17.0
  - share_audit_dashboard: 0.5.0
  - sharebymail: 1.24.0
  - sharereview: 2.3.0
  - spreed: 24.0.5
  - support: 6.0.0
  - survey_client: 6.0.0-dev.0
  - systemtags: 1.24.0
  - text: 8.0.0
  - theming: 2.9.0
  - twofactor_backupcodes: 1.23.0
  - twofactor_nextcloud_notification: 8.0.0
  - twofactor_totp: 16.0.0
  - updatenotification: 1.24.0
  - user_ldap: 1.25.0
  - user_status: 1.14.0
  - viewer: 7.0.0-dev.0
  - weather_status: 1.14.0
  - webhook_listeners: 1.6.0
  - whiteboard: 2.0.0
  - workflowengine: 2.16.0
Disabled:
  - encryption: 2.22.0
  - mail_roundcube: 1.2.2 (installed 1.2.2)
  - suspicious_login: 12.0.0-dev.0
  - testing: 1.23.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Additional info

No response