[Bug]: Files search provider does not always handle large external file repositories well

⚠️ 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 unified search is broken for files and does not return any results. Using the search functionality of Nextcloud within the Webgui, results are only obtained for anything that is not a file. Issuing a GET operation on ocs/v2.php/search/providers we can verify that the suitable provider is registered

      {
        "id": "files",
        "name": "Files",
        "order": "5",
        "#text": "..."
      }

If issuing a manual GET request along the lines

`ocs/v2.php/search/providers/files/search?term=my_test_file...`

Nothing happens, and no reply is received. In contrast, for e.g. ocs/v2.php/search/providers/contacts/search? replies are received as expected.

Correspondingly, when searching for files in the Webgui, the search simply remains stuck on waiting forever.

Steps to reproduce

1. Navigate to the Nextcloud webgui
2. Search for a known, existing file within the own folder
3. No results are returned, and search remains perpetually waiting.

Expected behavior

File search should return a reply to get GET request and provide list of matching files.

Installation method

Community Docker image

Nextcloud Server version

25

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database engine version

MariaDB

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

Fresh Nextcloud Server install

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": {
        "htaccess.RewriteBase": "\/",
        "memcache.local": "\\OC\\Memcache\\Redis",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "overwriteprotocol": "https",
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "***REMOVED SENSITIVE VALUE***"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "25.0.8.2",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "25",
        "mail_smtpsecure": "tls",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "default_phone_region": "DE",
        "maintenance": false,
        "twofactor_enforced": "true",
        "twofactor_enforced_groups": [],
        "twofactor_enforced_excluded_groups": [],
        "theme": "",
        "loglevel": 2
    }
}

List of activated Apps

Enabled:
  - activity: 2.17.0
  - cfg_share_links: 4.1.0
  - circles: 25.0.0
  - cloud_federation_api: 1.8.0
  - comments: 1.15.0
  - contactsinteraction: 1.6.0
  - dashboard: 7.5.0
  - dav: 1.24.0
  - drawio: 2.1.1
  - federatedfilesharing: 1.15.0
  - federation: 1.15.0
  - files: 1.20.1
  - files_external: 1.17.0
  - files_markdown: 2.4.1
  - files_pdfviewer: 2.6.0
  - files_rightclick: 1.4.0
  - files_sharing: 1.17.0
  - files_trashbin: 1.15.0
  - files_versions: 1.18.0
  - firstrunwizard: 2.14.0
  - geoblocker: 0.5.11
  - groupfolders: 13.1.3
  - logreader: 2.10.0
  - lookup_server_connector: 1.13.0
  - nextcloud_announcements: 1.14.0
  - notifications: 2.13.1
  - oauth2: 1.13.1
  - password_policy: 1.15.0
  - photos: 2.0.1
  - privacy: 1.9.0
  - provisioning_api: 1.15.0
  - ransomware_protection: 1.14.0
  - recommendations: 1.4.0
  - related_resources: 1.0.4
  - serverinfo: 1.15.0
  - settings: 1.7.0
  - sharebymail: 1.15.0
  - support: 1.8.0
  - survey_client: 1.13.0
  - systemtags: 1.15.0
  - text: 3.6.0
  - theming: 2.0.1
  - twofactor_backupcodes: 1.14.0
  - twofactor_webauthn: 1.2.0
  - updatenotification: 1.15.0
  - user_status: 1.5.0
  - viewer: 1.9.0
  - weather_status: 1.5.0
  - workflowengine: 2.7.0
Disabled:
  - admin_audit
  - bruteforcesettings
  - encryption
  - sharepermissions
  - suspicious_login
  - twofactor_totp
  - user_ldap

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

The Nextcloud logs contain sensitive information, with the failed search queries making no appearance (to the best of my judgment). Hence omitted. I.e., search queries for files are simply swallowed without any appearance in the log.

Additional info

Using primary and secondary DB, running behind a traefik proxy.

Start by reproducing the files provider request at ocs/v2.php/search/providers/files/search and compare it with the contacts provider request. Trace the files search handling for an external repository and verify that a request returns matching results rather than waiting indefinitely.