{"record":{"id":"5f43c14732781835","repo":"langchain-ai/langgraph","slug":"please-install-langchain-pip-install-langchain","errorCode":null,"errorMessage":"Please install langchain (`pip install langchain`) to use '<provider>:<model>' string syntax for `model` parameter.","messagePattern":"Please install langchain \\(`pip install langchain`\\) to use '<provider>:<model>' string syntax for `model` parameter\\.","errorType":"exception","errorClass":"ImportError","httpStatus":null,"severity":"error","filePath":"libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py","lineNumber":575,"sourceCode":"        tool_node = tools\n    else:\n        llm_builtin_tools = [t for t in tools if isinstance(t, dict)]\n        tool_node = ToolNode([t for t in tools if not isinstance(t, dict)])\n        tool_classes = list(tool_node.tools_by_name.values())\n\n    is_dynamic_model = not isinstance(model, (str, Runnable)) and callable(model)\n    is_async_dynamic_model = is_dynamic_model and inspect.iscoroutinefunction(model)\n\n    tool_calling_enabled = len(tool_classes) > 0\n\n    if not is_dynamic_model:\n        if isinstance(model, str):\n            try:\n                from langchain.chat_models import (  # type: ignore[import-not-found]\n                    init_chat_model,\n                )\n            except ImportError:\n                raise ImportError(\n                    \"Please install langchain (`pip install langchain`) to \"\n                    \"use '<provider>:<model>' string syntax for `model` parameter.\"\n                )\n\n            model = cast(BaseChatModel, init_chat_model(model))\n\n        if (\n            _should_bind_tools(model, tool_classes, num_builtin=len(llm_builtin_tools))  # type: ignore[arg-type]\n            and len(tool_classes + llm_builtin_tools) > 0\n        ):\n            model = cast(BaseChatModel, model).bind_tools(\n                tool_classes + llm_builtin_tools  # type: ignore[operator]\n            )\n\n        static_model: Runnable | None = _get_prompt_runnable(prompt) | model  # type: ignore[operator]\n    else:\n        # For dynamic models, we'll create the runnable at runtime\n        static_model = None","sourceCodeStart":557,"sourceCodeEnd":593,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py#L557-L593","documentation":"Error \"Please install langchain (`pip install langchain`) to use '<provider>:<model>' string syntax for `model` parameter.\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/prebuilt/langgraph/prebuilt/chat_agent_executor.py:575 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"38031739e551638e373fb553453256c23feeb41f","analyzedAt":"2026-08-26T18:02:49.312Z","schemaVersion":2},"datasetVersion":"2026-08-26T21:11:00.512Z"}