[Bug]: S3 storage (OCI Object Storage compatible) fails to sync files when filename contains accented UTF-8 characters

[HDB-Systems]

⚠️ 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

Since early November 2025, my Nextcloud instance started experiencing a critical issue when uploading or syncing files whose filenames contain accented UTF-8 characters (á, é, í, ó, ú, ç, ã, etc.).

The issue affects both:

Nextcloud Windows Desktop Client

Nextcloud Web Interface

Files without accents upload normally.
Files with accents always fail, regardless of size.

This behavior started suddenly, without any configuration changes on my side — possibly after a recent Nextcloud update or a change in the S3-compatible endpoint behavior from Oracle Cloud.

Steps to reproduce

1. Use Nextcloud configured with external object storage via S3 backend.
2. Backend: Oracle Cloud Object Storage – S3 compatible private endpoint.
3. Attempt to upload a file named e.g.:
   áéíóú.pdf
   reunião.docx
   apresentação.pptx
4. Upload via:
   Web interface → fails
   Windows client → fails
5. Rename the same file to a name without accents.
6. Upload again → works normally.

Expected behavior

Files with UTF-8 accented characters in their names should sync/upload normally, as in all previous Nextcloud versions and as per standard S3 behavior.

Nextcloud Server version

32

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.3

Web server

Nginx

Database engine version

PostgreSQL

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

Updated from a MINOR version (ex. 32.0.1 to 32.0.2)

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": {
        "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
            }
        ],
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "objectstore": {
            "class": "\\OC\\Files\\ObjectStore\\S3",
            "arguments": {
                "bucket": "drive",
                "region": "sa-saopaulo-1",
                "hostname": "xxxxx-xxxxxxx.private.compat.objectstorage.sa-saopaulo-1.oci.customer-oci.com",
                "port": "",
                "storageClass": "",
                "objectPrefix": "urn:oid:",
                "autocreate": true,
                "use_ssl": true,
                "use_path_style": true,
                "legacy_auth": false,
                "key": "***REMOVED SENSITIVE VALUE***",
                "secret": "***REMOVED SENSITIVE VALUE***"
            }
        },
        "upgrade.disable-web": true,
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "drive.acme.com.br"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "32.0.1.2",
        "overwrite.cli.url": "https:\/\/xxxx.acme.com.br",
        "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,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpsecure": "ssl",
        "mail_smtpauth": 1,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "maintenance_window_start": "21",
        "default_phone_region": "BR",
        "loglevel": 2,
        "allowed_admin_ranges": [
            "127.0.0.1\/8",
            "172.30.50.0\/24"
        ],
        "skeletondirectory": "",
        "allow_local_remote_servers": true,
        "max_chunk_size": 1097152000
    }
}

List of activated Apps

Enabled:
  - activity: 5.0.0-dev.0
  - admin_audit: 1.22.0
  - app_api: 32.0.0
  - bruteforcesettings: 5.0.0-dev.0
  - circles: 32.0.0
  - cloud_federation_api: 1.16.0
  - comments: 1.22.0
  - contactsinteraction: 1.13.1
  - dashboard: 7.12.0
  - dav: 1.34.2
  - federatedfilesharing: 1.22.0
  - federation: 1.22.0
  - files: 2.4.0
  - files_downloadlimit: 5.0.0-dev.0
  - files_pdfviewer: 5.0.0-dev.0
  - files_reminders: 1.5.0
  - files_sharing: 1.24.0
  - files_trashbin: 1.22.0
  - files_versions: 1.25.0
  - firstrunwizard: 5.0.0-dev.0
  - groupfolders: 20.1.3
  - impersonate: 3.0.0
  - logreader: 5.0.0-dev.0
  - lookup_server_connector: 1.20.0
  - nextcloud_announcements: 4.0.0-dev.0
  - notifications: 5.0.0-dev.0
  - oauth2: 1.20.0
  - password_policy: 4.0.0-dev.0
  - photos: 5.0.0-dev.1
  - privacy: 4.0.0-dev.0
  - profile: 1.1.0
  - provisioning_api: 1.22.0
  - recommendations: 5.0.0-dev.0
  - related_resources: 3.0.0-dev.0
  - serverinfo: 4.0.0-dev.0
  - settings: 1.15.1
  - sharebymail: 1.22.0
  - support: 4.0.0-dev.0
  - survey_client: 4.0.0-dev.0
  - systemtags: 1.22.0
  - text: 6.0.1
  - theming: 2.7.0
  - twofactor_backupcodes: 1.21.0
  - twofactor_totp: 14.0.0
  - updatenotification: 1.22.0
  - user_oidc: 8.1.0
  - user_status: 1.12.0
  - viewer: 5.0.0-dev.0
  - weather_status: 1.12.0
  - webhook_listeners: 1.3.0
  - workflowengine: 2.14.0
Disabled:
  - encryption: 2.20.0
  - files_external: 1.24.0
  - suspicious_login: 10.0.0-dev.0
  - twofactor_nextcloud_notification: 6.0.0-dev.0
  - user_ldap: 1.23.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

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{"reqId":"Him0dhmiP2fJBapmPxsb","level":3,"time":"2025-11-13T20:52:16+00:00","remoteAddr":"172.30.50.89","user":"sergio.souza@acme.com.br","app":"no app in context","method":"PUT","url":"/remote.php/dav/files/sergio.souza@acme.com.br/Projetos/TI/ODL/docs/Kick-off%20do%20Projeto%20Plataforma%20de%20Agendamento%20-%20Ocean%C3%A1rio%20de%20Lisboa.pptx","message":"Uncaught exception","userAgent":"Mozilla/5.0 (Windows) mirall/4.0.1 (build 20251027) (Nextcloud, windows-10.0.26200 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"32.0.1.2","clientReqId":"618b8ad3-a278-4259-aa24-a9a95068dcb4","exception":{"Exception":"Sabre\\DAV\\Exception","Message":"Erro ao copiar o arquivo para o local de destino (copiado: -1 byte, tamanho de arquivo esperado: 15975332 bytes)","Code":0,"Trace":[{"file":"/var/www/html/apps/dav/lib/Connector/Sabre/Directory.php","line":119,"function":"put","class":"OCA\\DAV\\Connector\\Sabre\\File","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php","line":1098,"function":"createFile","class":"OCA\\DAV\\Connector\\Sabre\\Directory","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/sabre/dav/lib/DAV/CorePlugin.php","line":504,"function":"createFile","class":"Sabre\\DAV\\Server","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"httpPut","class":"Sabre\\DAV\\CorePlugin","type":"->","args":[{"__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"/var/www/html/3rdparty/sabre/dav/lib/DAV/Server.php","line":472,"function":"emit","class":"Sabre\\DAV\\Server","type":"->","args":["method:PUT",[{"__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]]},{"file":"/var/www/html/apps/dav/lib/Connector/Sabre/Server.php","line":211,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->","args":[{"__class__":"Sabre\\HTTP\\Request"},{"__class__":"Sabre\\HTTP\\Response"}]},{"file":"/var/www/html/apps/dav/lib/Server.php","line":424,"function":"start","class":"OCA\\DAV\\Connector\\Sabre\\Server","type":"->","args":[]},{"file":"/var/www/html/apps/dav/appinfo/v2/remote.php","line":22,"function":"exec","class":"OCA\\DAV\\Server","type":"->","args":[]},{"file":"/var/www/html/remote.php","line":151,"args":["/var/www/html/apps/dav/appinfo/v2/remote.php"],"function":"require_once"}],"File":"/var/www/html/apps/dav/lib/Connector/Sabre/File.php","Line":242,"message":"Uncaught exception","exception":{},"CustomMessage":"Uncaught exception"}}

Additional info

I´m using docker

[provokateurin]

Fixed by #55717