langchain-core breaking changes

1.3.3

5 breaking changes, first published May 5, 2026.

• Signature changed langchain_core.load.load.load
  Was def load(obj: Any, *, allowed_objects: Iterable[AllowedObject] | Literal['all', 'core'] = 'core', secrets_map: dict[str, str] | None = None, valid_namespaces: list[str] | None = None, secrets_from_env: bool = False... pypi.org
• Signature changed langchain_core.load.load.Reviver.__init__
  Was def __init__(self, allowed_objects: Iterable[AllowedObject] | Literal['all', 'core'] = 'core', secrets_map: dict[str, str] | None = None, valid_namespaces: list[str] | None = None, secrets_from_env: bool = False... pypi.org
• Signature changed langchain_core.load.loads
  Was def loads(text: str, *, allowed_objects: Iterable[AllowedObject] | Literal['all', 'core'] = 'core', secrets_map: dict[str, str] | None = None, valid_namespaces: list[str] | None = None, secrets_from_env: bool = False... pypi.org
• Signature changed langchain_core.runnables.history.load
  Was def load(obj: Any, *, allowed_objects: Iterable[AllowedObject] | Literal['all', 'core'] = 'core', secrets_map: dict[str, str] | None = None, valid_namespaces: list[str] | None = None, secrets_from_env: bool = False... pypi.org
• Signature changed langchain_core.tracers.log_stream.load
  Was def load(obj: Any, *, allowed_objects: Iterable[AllowedObject] | Literal['all', 'core'] = 'core', secrets_map: dict[str, str] | None = None, valid_namespaces: list[str] | None = None, secrets_from_env: bool = False... pypi.org

1.3.0

5 breaking changes, first published April 17, 2026.

• Signature changed langchain_core.callbacks.CallbackManager.configure
  Was @classmethod def configure(cls, inheritable_callbacks: Callbacks = None, local_callbacks: Callbacks = None, verbose: bool = False, inheritable_tags: list[str] | None = None, local_tags: list[str] | None = None, inheritable_metadata... pypi.org
• Signature changed langchain_core.tracers.BaseTracer.__init__
  Was def __init__(self, *, _schema_format: Literal['original', 'streaming_events', 'original+chat'] = 'original', **kwargs: Any) -> None; now def __init__(self, *, _schema_format: Literal['original', 'streaming_events', 'original+chat'] =... pypi.org
• Signature changed langchain_core.tracers.BaseTracer.order_map
  Was order_map: dict[UUID, tuple[UUID, str]]; now order_map. pypi.org
• Signature changed langchain_core.tracers.BaseTracer.run_map
  Was run_map: dict[str, Run]; now run_map. pypi.org
• Signature changed langchain_core.tracers.LangChainTracer.__init__
  Was def __init__(self, example_id: UUID | str | None = None, project_name: str | None = None, client: Client | None = None, tags: list[str] | None = None, **kwargs: Any) -> None; now def __init__(self, example_id: UUID | str | None = None... pypi.org

1.2.22

3 breaking changes, first published March 24, 2026.

• Signature changed langchain_core.prompts.load_prompt
  Was def load_prompt(path: str | Path, encoding: str | None = None) -> BasePromptTemplate; now def load_prompt(path: str | Path, encoding: str | None = None, *, allow_dangerous_paths: bool = False) -> BasePromptTemplate. pypi.org
• Signature changed langchain_core.prompts.loading.load_prompt_from_config
  Was def load_prompt_from_config(config: dict) -> BasePromptTemplate; now def load_prompt_from_config(config: dict, *, allow_dangerous_paths: bool = False) -> BasePromptTemplate. pypi.org
• Signature changed langchain_core.prompts.loading.type_to_loader_dict
  Was type_to_loader_dict: dict[str, Callable[[dict], BasePromptTemplate]]; now type_to_loader_dict: dict[str, Callable[..., BasePromptTemplate]]. pypi.org

1.2.15

4 breaking changes, first published February 23, 2026.

• Removed langchain_core.callbacks.manager.ConsoleCallbackHandler
  langchain_core.callbacks.manager.ConsoleCallbackHandler was removed in langchain-core 1.2.15 pypi.org
• Removed langchain_core.callbacks.manager.LangChainTracer
  langchain_core.callbacks.manager.LangChainTracer was removed in langchain-core 1.2.15 pypi.org
• Removed langchain_core.callbacks.manager.tracing_v2_callback_var
  langchain_core.callbacks.manager.tracing_v2_callback_var was removed in langchain-core 1.2.15 pypi.org
• Removed langchain_core.runnables.config.LangChainTracer
  langchain_core.runnables.config.LangChainTracer was removed in langchain-core 1.2.15 pypi.org

1.2.10

1 breaking change, first published February 10, 2026.

• Signature changed langchain_core.messages.utils.count_tokens_approximately
  Was def count_tokens_approximately(messages: Iterable[MessageLikeRepresentation], *, chars_per_token: float = 4.0, extra_tokens_per_message: float = 3.0, count_name: bool = True, tokens_per_image: int = 85, use_usage_metadata_scaling: bool... pypi.org

1.2.9

1 breaking change, first published February 5, 2026.

• Signature changed langchain_core.messages.utils.count_tokens_approximately
  Was def count_tokens_approximately(messages: Iterable[MessageLikeRepresentation], *, chars_per_token: float = 4.0, extra_tokens_per_message: float = 3.0, count_name: bool = True, tokens_per_image: int = 85) -> int; now def... pypi.org

Check your code

These are the changes. To see which of them reach your code, scan a public repository, or have your coding agent call check_code with your manifest or lockfile over MCP. The API reads every change in every version, not only the newest. On Team and up, a fix pull request opens for the changes that reach a connected repository. Nothing merges or deploys.