{"record":{"id":"05cd2e405d12e1c2","repo":"langflow-ai/langflow","slug":"failed-to-write-target-name-exc-strerror-or-ex","errorCode":null,"errorMessage":"Failed to write {target.name}: {exc.strerror or exc}","messagePattern":"Failed to write (.+?): (.+?)","errorType":"validation","errorClass":"UserComponentError","httpStatus":null,"severity":"error","filePath":"src/backend/base/langflow/agentic/services/user_components.py","lineNumber":297,"sourceCode":"    accumulates stray ``.tmp`` artifacts. ``os.replace`` is atomic on\n    POSIX and on Windows (since Python 3.3) when source and dest are on\n    the same filesystem — which they are here, both inside the user's\n    sandbox.\n    \"\"\"\n    # Use tempfile inside the SAME directory so os.replace stays\n    # cross-device-safe (replace requires source+dest on the same FS).\n    tmp_fd, tmp_name = tempfile.mkstemp(prefix=f\"{target.stem}.\", suffix=\".py.tmp\", dir=str(target.parent))\n    tmp_path = Path(tmp_name)\n    try:\n        with os.fdopen(tmp_fd, \"w\", encoding=\"utf-8\") as f:\n            f.write(text)\n        tmp_path.replace(target)\n    except OSError as exc:\n        # Clean up the tmp file (it might have data but is unreachable).\n        with contextlib.suppress(OSError):\n            tmp_path.unlink(missing_ok=True)\n        msg = f\"Failed to write {target.name}: {exc.strerror or exc}\"\n        raise UserComponentError(msg) from exc\n","sourceCodeStart":279,"sourceCodeEnd":298,"githubUrl":"https://github.com/langflow-ai/langflow/blob/976ec789d2886a86de109c044d089d68e96c9a35/src/backend/base/langflow/agentic/services/user_components.py#L279-L298","documentation":"Raised when the atomic write of the component file (tmp file + os.replace into <components_dir>/<ClassName>.py) fails with an OSError. The tmp file is unlinked before raising so no stray .py.tmp artifacts accumulate. As with the mkdir failure, the OS strerror is included — this is a host/filesystem problem, not a code problem.","triggerScenarios":"Disk fills up between mkdir and write; the target file is held open with a mandatory lock (Windows); the directory was removed concurrently; permission revoked mid-write.","commonSituations":"Transient disk-full on shared hosts; antivirus/indexer briefly locking freshly created files on Windows; concurrent registrations racing on the same class name.","solutions":["Read the strerror to identify the host-level cause (space, permissions, lock).","Retry the registration once — the write is atomic and a transient lock/space issue often clears.","On Windows, exclude the sandbox directory from antivirus scanning if 'file in use' errors recur.","Ensure only one process registers the same class_name at a time."],"exampleFix":null,"handlingStrategy":"retry","validationCode":null,"typeGuard":null,"tryCatchPattern":"for attempt in range(2):\n    try:\n        return register_user_component(user_id=uid, class_name=name, code=src)\n    except UserComponentError as e:\n        if str(e).startswith(\"Failed to write\") and attempt == 0:\n            continue  # transient lock / space: tmp file already cleaned up, safe to retry\n        raise","preventionTips":["Treat 'Failed to write' as a host-level signal — check disk and locks before blaming the code.","Exclude the sandbox dir from antivirus scanning on Windows hosts.","Serialize registrations of the same class name across processes."],"tags":["filesystem","atomic-write","retry","user-components"],"backgroundTag":null,"analyzedSha":"976ec789d2886a86de109c044d089d68e96c9a35","analyzedAt":"2026-08-14T18:23:12.227Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}