[Bug]: Exception: The bucket will not be created because the name is not dns compatible ( backblaze S3 bucket)

⚠️ 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

While trying to create a folder backed by backblaze S3 solution, nextcloud complains that the name is not DNS compatible.
I am following Backblaze instructions : https://www.backblaze.com/docs/cloud-storage-integrate-nextcloud-with-backblaze-b2

To do so, i've created a bucket like so :

named "rhebryn-archives", the endpoint is s3.us-west-004.backblazeb2.com

Yet, when trying to add the config as follow, nextcloud complains about an invalid dns name :

This may looks like a valid error, but there is no indication whatsoever on how to fix it

Steps to reproduce

1. Try to add a backblaze bucket in nextcloud
2. Save the configuration

Expected behavior

Having the bucket mounted

Nextcloud Server version

30

Operating system

Other

PHP engine version

PHP 8.2

Web server

None

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": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "cloud.retidurc.fr",
            "cloud.ryckaert.me",
            "cloud.zaziss.com"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "overwrite.cli.url": "https:\/\/cloud.retidurc.fr",
        "dbtype": "pgsql",
        "version": "30.0.6.2",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "dbpersistent": true,
        "installed": true,
        "maintenance": false,
        "theme": "",
        "loglevel": 0,
        "updater.release.channel": "stable",
        "app_install_overwrite": [
            "admin_notifications",
            "tasks",
            "ocr",
            "ransomware_detection",
            "calendar",
            "workflow_pdf_converter",
            "deck",
            "event_update_notification",
            "audioplayer",
            "metadata",
            "files_external_gdrive",
            "camerarawpreviews",
            "extract",
            "impersonate",
            "news",
            "polls",
            "ransomware_protection",
            "files_snapshots",
            "unsplash",
            "dropit",
            "checksum",
            "mindmap_app",
            "breezedark",
            "contacts",
            "keeporsweep",
            "social",
            "dicomviewer",
            "occweb",
            "files_archive",
            "duplicatefinder",
            "maps",
            "quicknotes"
        ],
        "mail_smtpmode": "sendmail",
        "mail_sendmailmode": "pipe",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "ldapIgnoreNamingRules": false,
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "1025",
        "encryption.legacy_format_support": false,
        "filelocking.enabled": true,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "timeout": 0
        },
        "debug": false,
        "profiler": false,
        "default_phone_region": "FR",
        "enabledPreviewProviders": [
            "OC\\Preview\\PDF",
            "OC\\Preview\\Image",
            "OC\\Preview\\Photoshop",
            "OC\\Preview\\TIFF",
            "OC\\Preview\\SVG",
            "OC\\Preview\\Movie",
            "OC\\Preview\\MKV",
            "OC\\Preview\\MP4",
            "OC\\Preview\\AVI",
            "OC\\Preview\\MP3",
            "OC\\Preview\\TXT",
            "OC\\Preview\\MarkDown",
            "OC\\Preview\\OpenDocument",
            "OC\\Preview\\Krita"
        ],
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpstreamoptions": {
            "ssl": {
                "allow_self_signed": true,
                "verify_peer": false,
                "verify_peer_name": false
            }
        },
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "maintenance_window_start": 2
    }
}

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

No response

Start by reproducing the external-storage configuration from the issue with the Backblaze S3 endpoint and bucket name. Trace the configuration validation that reports the DNS compatibility error and compare it with the documented Backblaze setup. Done means the valid bucket configuration is accepted and the bucket can be mounted.