[Bug]: SMB/CIFS and "Move or Copy" / "Delete folder" failed on some elements

⚠️ 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

These actions are performed via the web GUI, Files app.
The external storage is added as a folder via SMB/CIFS in Settings, from a share hosted on a TrueNAS Core VM on the same physical machine (simple mirror VDEV on two HDDs).

Large folders can fail even when there is no additional load on the Nextcloud or SMB/CIFS server, or the overall VM host. Additionally, even small folders can fail when concurrently with this attempt to move files to the SMB/CIFS, I am also syncing files from my phone at approximately 1 file per 3 seconds to the same SMB/CIFS share.

I can see in the samba logs on the TrueNAS Core host that even after the Nextcloud web GUI error is presented, there is still a lot of activity happening. Files being moved or copied, seemingly until the transfer is all but completed.

The issue I face is when attempting to move or copy folders from local storage into external storage. Sometimes the attempt results in the following error:
"Move or copy" failed on some elements

However, there is no additional information to be found anywhere in the web GUI, nor any logs I have looked at. The move is at least partially executed as a copy, leaving the source intact and some (or even most/all files but without proper creation/modification dates set) also at the destination.

Attempting to delete a partially moved folder from the destination SMB/CIFS storage, sometimes results in the following error:
"Delete folder" failed on some elements
However, waiting for a little while seems to actually result in the files being deleted.

The SMB/CIFS external storage implementation does not appear robust when interfaced via the web GUI Files app.

Steps to reproduce

1. Set up files on local storage, and add an external storage location via SMB/CIFS
2. Move or Copy a large folder (hundreds of files, several GB in size) from local storage to a folder on the external storage
3. Sometimes this results in the error '"Move or copy" failed on some elements', without additional information or logs
4. Wait a little moment, and it seems the transfer is still ongoing in the background. Eventually you may have a copy in the destination folder, partial or seemingly in full, and also the original folder still remains with all files intact at the source in case of a Move.

Expected behavior

Better information and logging for errors.
Robust interaction with SMB/CIFS shares for all file transactions.

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Apache (supported)

Database engine version

PostgreSQL

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": {
        "one-click-instance": true,
        "one-click-instance.user-limit": 100,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "appsallowlist": false,
        "check_data_directory_permissions": false,
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "overwritehost": "mydomain",
        "overwriteprotocol": "https",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "mydomain"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "31.0.8.1",
        "overwrite.cli.url": "https:\/\/mydomain\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "updatedirectory": "\/nc-updater",
        "loglevel": "2",
        "log_type": "file",
        "logfile": "\/var\/www\/html\/data\/nextcloud.log",
        "log_rotate_size": "10485760",
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "preview_max_x": 2048,
        "preview_max_y": 2048,
        "jpeg_quality": 60,
        "enabledPreviewProviders": {
            "1": "OC\\Preview\\Image",
            "2": "OC\\Preview\\MarkDown",
            "3": "OC\\Preview\\MP3",
            "4": "OC\\Preview\\TXT",
            "5": "OC\\Preview\\OpenDocument",
            "6": "OC\\Preview\\Movie",
            "7": "OC\\Preview\\Krita",
            "0": "OC\\Preview\\Imaginary",
            "23": "OC\\Preview\\ImaginaryPDF"
        },
        "enable_previews": true,
        "upgrade.disable-web": true,
        "mail_smtpmode": "smtp",
        "trashbin_retention_obligation": "auto, 30",
        "versions_retention_obligation": "auto, 30",
        "activity_expire_days": "30",
        "simpleSignUpLink.shown": false,
        "share_folder": "\/Shared",
        "one-click-instance.link": "https:\/\/nextcloud.com\/all-in-one\/",
        "upgrade.cli-upgrade-link": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/2726",
        "allow_local_remote_servers": true,
        "davstorage.request_timeout": 3600,
        "htaccess.RewriteBase": "\/",
        "dbpersistent": false,
        "files_external_allow_create_new_local": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "maintenance_window_start": 100,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "memories.db.triggers.fcu": true,
        "memories.exiftool": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/exiftool-amd64-musl",
        "memories.vod.path": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/go-vod-amd64",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "updatechecker": false,
        "documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
        "DOMAIN": "mydomain"
    }
}

List of activated Apps

Enabled:
  - activity: 4.0.0
  - admin_audit: 1.21.0
  - bruteforcesettings: 4.0.0
  - calendar: 5.5.1
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contacts: 7.2.6
  - contactsinteraction: 1.12.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - deck: 1.15.2
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_external: 1.23.0
  - files_fulltextsearch: 31.0.0
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - fulltextsearch: 31.0.0
  - fulltextsearch_elasticsearch: 31.0.0
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - memories: 7.6.2
  - nextcloud-aio: 0.8.0
  - nextcloud_announcements: 3.0.0
  - notes: 4.12.3
  - notifications: 4.0.0
  - notify_push: 1.2.0
  - oauth2: 1.19.1
  - password_policy: 3.0.0
  - photos: 4.0.0
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - richdocuments: 8.7.4
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - spreed: 21.1.4
  - support: 3.0.0
  - survey_client: 3.0.0
  - systemtags: 1.21.1
  - tasks: 0.16.1
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - twofactor_totp: 13.0.0-dev.0
  - updatenotification: 1.21.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - whiteboard: 1.1.3
  - workflowengine: 2.13.0
Disabled:
  - app_api: 5.0.2 (installed 4.0.6)
  - encryption: 2.19.0
  - suspicious_login: 9.0.1
  - twofactor_nextcloud_notification: 5.0.0
  - user_ldap: 1.22.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

Nothing relevant found.

Additional info

No response

No source file or test is identified in the report. Start by reproducing the Files app SMB/CIFS move or copy and delete-folder actions with a large folder and concurrent syncing, then inspect nextcloud.log and the Samba logs; done means failures are accurately reported and the transfer or deletion completes reliably.