WebSocket Connection Error

[mononym]

I tried to look into why queued documents are not processed. In the end, it was only a question of enough patience.
But I noticed an error in Settings > System Status (top right) > "WebSocket Connection"

{
    "pngx_version": "2.20.15",
    "server_os": "Linux-6.8.0-111-generic-x86_64-with-glibc2.39",
    "install_type": "bare-metal",
    "storage": {
        "total": 92342554660,
        "available": 43966247799
    },
    "database": {
        "type": "postgresql",
        "url": "dbd53e3dca2edd46f2b70b12cc2d9b0c26",
        "status": "OK",
        "error": null,
        "migration_status": {
            "latest_migration": "documents.1075_workflowaction_order",
            "unapplied_migrations": []
        }
    },
    "tasks": {
        "redis_url": "redis://redis-d53e3dca-2edd-46f2-b70b-12cc2d9b0c26:6379",
        "redis_status": "OK",
        "redis_error": null,
        "celery_status": "OK",
        "celery_url": "celery@d53e3dca-2edd-46f2-b70b-12cc2d9b0c26",
        "celery_error": null,
        "index_status": "OK",
        "index_last_modified": "2026-05-17T12:53:29.784656Z",
        "index_error": null,
        "classifier_status": "OK",
        "classifier_last_trained": "2026-05-17T12:05:02.705492Z",
        "classifier_error": null,
        "sanity_check_status": "OK",
        "sanity_check_last_run": "2026-05-17T00:30:02.789882Z",
        "sanity_check_error": null
    },
    "websocket_connected": "ERROR"
}

Don't know how critical that is...