{"record":{"id":"4453d44e05f89824","repo":"bytedance/deer-flow","slug":"scheduler-multi-instance-true-requires-database-ba","errorCode":null,"errorMessage":"scheduler.multi_instance=true requires database.backend='postgres'. database.backend is '{backend}'. Set scheduler.multi_instance=false or configure Postgres.","messagePattern":"scheduler\\.multi_instance=true requires database\\.backend='postgres'\\. database\\.backend is '(.+?)'\\. Set scheduler\\.multi_instance=false or configure Postgres\\.","errorType":"console","errorClass":"SystemExit","httpStatus":null,"severity":"critical","filePath":"backend/app/gateway/deps.py","lineNumber":96,"sourceCode":"    This gate runs once at startup before any persistence engine is\n    initialised so the error message is clear and the process exits\n    immediately.\n    \"\"\"\n    try:\n        workers = int(os.environ.get(\"GATEWAY_WORKERS\", \"1\"))\n    except (TypeError, ValueError):\n        workers = 1\n\n    scheduler = getattr(config, \"scheduler\", None)\n    multi_instance_requested = bool(getattr(scheduler, \"multi_instance\", False))\n    multi_instance_scheduler = bool(getattr(scheduler, \"enabled\", False) and multi_instance_requested)\n\n    backend = getattr(config.database, \"backend\", None)\n    run_events_backend = getattr(getattr(config, \"run_events\", None), \"backend\", None)\n    run_ownership = getattr(config, \"run_ownership\", None)\n\n    if multi_instance_requested and backend != \"postgres\":\n        raise SystemExit(f\"scheduler.multi_instance=true requires database.backend='postgres'. database.backend is '{backend}'. Set scheduler.multi_instance=false or configure Postgres.\")\n    if multi_instance_requested and run_events_backend != \"db\":\n        raise SystemExit(f\"scheduler.multi_instance=true requires run_events.backend='db'. run_events.backend is '{run_events_backend}'. Set scheduler.multi_instance=false or configure run_events.backend: db.\")\n    if multi_instance_requested and (run_ownership is None or not run_ownership.heartbeat_enabled):\n        raise SystemExit(\"scheduler.multi_instance=true requires run_ownership.heartbeat_enabled=true so peer runs retain a valid lease. Set scheduler.multi_instance=false or enable run ownership heartbeats.\")\n\n    if workers <= 1:\n        return\n\n    if config.scheduler.enabled and not multi_instance_scheduler:\n        raise SystemExit(f\"GATEWAY_WORKERS={workers} cannot run with scheduler.enabled=true because each worker starts its own scheduler. Set GATEWAY_WORKERS=1, scheduler.multi_instance=true, or scheduler.enabled=false.\")\n\n    if _browser_tools_enabled_in_config(config):\n        raise SystemExit(browser_multi_worker_error(workers))\n\n    if backend != \"postgres\":\n        raise SystemExit(f\"GATEWAY_WORKERS={workers} requires database.backend='postgres', but database.backend is '{backend}'. SQLite cannot support concurrent multi-process access. Set GATEWAY_WORKERS=1 or switch to Postgres.\")\n\n    if run_events_backend != \"db\":","sourceCodeStart":78,"sourceCodeEnd":114,"githubUrl":"https://github.com/bytedance/deer-flow/blob/1dd6ba1acb03700589994b0366c5d1c7d05e2eff/backend/app/gateway/deps.py#L78-L114","documentation":"SystemExit raised at Gateway startup (deps.py validation) when scheduler.multi_instance=true but database.backend is not 'postgres'. Multi-instance scheduling relies on Postgres-level coordination (row locks / SKIP LOCKED-style claiming) that SQLite/memory backends cannot provide, so the process refuses to boot rather than double-firing scheduled tasks.","triggerScenarios":"config.yaml sets scheduler.multi_instance: true (checked regardless of scheduler.enabled) while database.backend is sqlite or memory; or GATEWAY_WORKERS>1 with multi_instance set but the DB was left on sqlite.","commonSituations":"Scaling a single-node sqlite deployment out to multiple workers/replicas; copying config between environments (dev sqlite vs prod postgres) without flipping the database backend.","solutions":["Set database.backend: postgres (with a valid postgres URL) in config.yaml","Or set scheduler.multi_instance: false if running a single instance","Then restart the Gateway and verify it boots"],"exampleFix":"# config.yaml\n# before\ndatabase:\n  backend: sqlite\nscheduler:\n  multi_instance: true\n# after\ndatabase:\n  backend: postgres\n  url: postgresql+asyncpg://user:pass@host/deerflow\nscheduler:\n  multi_instance: true","handlingStrategy":"validation","validationCode":"# Preflight before launching multi-instance scheduler mode\nfrom app.config import load_config\ncfg = load_config()\nassert not (getattr(getattr(cfg, \"scheduler\", None), \"multi_instance\", False) and cfg.database.backend != \"postgres\"), \"multi_instance needs postgres\"","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Run a config preflight (make doctor / config validation) in CI for every environment's config.yaml","Treat scheduler.multi_instance as a bundle: postgres + run_events db + heartbeats","Keep dev (sqlite) and prod (postgres) configs in separate checked templates so flags don't leak across"],"tags":["config","startup","scheduler","postgres","system-exit","gateway"],"backgroundTag":null,"analyzedSha":"1dd6ba1acb03700589994b0366c5d1c7d05e2eff","analyzedAt":"2026-08-14T21:20:34.804Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}