{"record":{"id":"f5265f0debc2a120","repo":"langchain-ai/langchain","slug":"tracing-using-langchaintracerv1-is-no-longer-suppo","errorCode":null,"errorMessage":"Tracing using LangChainTracerV1 is no longer supported. Please set the LANGCHAIN_TRACING_V2 environment variable to enable tracing instead.","messagePattern":"Tracing using LangChainTracerV1 is no longer supported\\. Please set the LANGCHAIN_TRACING_V2 environment variable to enable tracing instead\\.","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"libs/core/langchain_core/callbacks/manager.py","lineNumber":2506,"sourceCode":"        callback_manager.add_metadata(local_metadata or {}, inherit=False)\n    if tracing_tags:\n        callback_manager.add_tags(tracing_tags.copy())\n\n    v1_tracing_enabled_ = env_var_is_set(\"LANGCHAIN_TRACING\") or env_var_is_set(\n        \"LANGCHAIN_HANDLER\"\n    )\n\n    tracer_v2 = tracing_v2_callback_var.get()\n    tracing_v2_enabled_ = _tracing_v2_is_enabled()\n\n    if v1_tracing_enabled_ and not tracing_v2_enabled_:\n        # if both are enabled, can silently ignore the v1 tracer\n        msg = (\n            \"Tracing using LangChainTracerV1 is no longer supported. \"\n            \"Please set the LANGCHAIN_TRACING_V2 environment variable to enable \"\n            \"tracing instead.\"\n        )\n        raise RuntimeError(msg)\n\n    tracer_project = _get_tracer_project()\n    debug = _get_debug()\n    if verbose or debug or tracing_v2_enabled_:\n        if verbose and not any(\n            isinstance(handler, StdOutCallbackHandler)\n            for handler in callback_manager.handlers\n        ):\n            if debug:\n                pass\n            else:\n                callback_manager.add_handler(StdOutCallbackHandler(), inherit=False)\n        if debug and not any(\n            isinstance(handler, ConsoleCallbackHandler)\n            for handler in callback_manager.handlers\n        ):\n            callback_manager.add_handler(ConsoleCallbackHandler())\n        if tracing_v2_enabled_ and not any(","sourceCodeStart":2488,"sourceCodeEnd":2524,"githubUrl":"https://github.com/langchain-ai/langchain/blob/e32fa9a52eab3b61ad7a45399bfde59b3e580fc4/libs/core/langchain_core/callbacks/manager.py#L2488-L2524","documentation":"In `_configure` (manager.py ~2506), if v1 tracing is enabled (`LANGCHAIN_TRACING_V1`/LangChainTracerV1) but v2 is not (`LANGCHAIN_TRACING_V2` unset/false), a `RuntimeError` is raised: LangChainTracerV1 tracing was removed. The library refuses to run with a v1-only configuration rather than silently not tracing.","triggerScenarios":"Setting `LANGCHAIN_TRACING_V1=true` (or passing a LangChainTracerV1 via env/callbacks) without `LANGCHAIN_TRACING_V2=true`; legacy deployments with old env var sets; .env files carried over from pre-0.1 projects.","commonSituations":"Upgrading old projects that used LANGCHAIN_TRACING_V1; CI pipelines with stale env matrices; copied docker-compose/k8s manifests still exporting v1 vars. When both are set, v1 is silently ignored, so the error only appears for v1-only configs.","solutions":["Set `LANGCHAIN_TRACING_V2=true` (and `LANGCHAIN_API_KEY`, optionally `LANGCHAIN_PROJECT`) — the error is suppressed once v2 is on","Remove `LANGCHAIN_TRACING_V1` and any LangChainTracerV1 references entirely","Search the repo/deploy configs for the v1 variable: `grep -r LANGCHAIN_TRACING_V1 .`","After enabling v2, confirm traces appear in the LangSmith project named by LANGCHAIN_PROJECT"],"exampleFix":"# before\nLANGCHAIN_TRACING_V1=true\nLANGCHAIN_API_KEY=ls__...\n\n# after\nLANGCHAIN_TRACING_V2=true\nLANGCHAIN_API_KEY=ls__...\nLANGCHAIN_PROJECT=my-project","handlingStrategy":"validation","validationCode":"import os\n\ndef tracing_config_ok() -> bool:\n    v1 = os.environ.get('LANGCHAIN_TRACING_V1')\n    v2 = os.environ.get('LANGCHAIN_TRACING_V2')\n    return not (v1 and not _truthy(v2))\n\ndef _truthy(v):\n    return str(v).lower() in {'1', 'true', 'yes'}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Delete LANGCHAIN_TRACING_V1 from all env files and deploy manifests","Standardize on LANGCHAIN_TRACING_V2 + LANGCHAIN_API_KEY (+ LANGCHAIN_PROJECT)","Add a startup assertion that no v1 variables are set"],"tags":["tracing","langsmith","environment","migration"],"backgroundTag":null,"analyzedSha":"e32fa9a52eab3b61ad7a45399bfde59b3e580fc4","analyzedAt":"2026-08-14T18:42:09.092Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}