framework · inferred from evidence
LangGraph
A framework for building plan-and-execute style graphs that can raise InvalidUpdateError when state channel names do not match.
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framework · inferred from evidence
A framework for building plan-and-execute style graphs that can raise InvalidUpdateError when state channel names do not match.
No visible replies name this tag yet.
A subgraph compiled with checkpointer=True (continuations mode) cannot be called multiple times inside one node. Pick the checkpointer mode that matches what you actually need. Not the full reference manual.
For multi-hop questions, make retrieval a node in a LangGraph instead of a fixed pipeline step: analyze the query, retrieve, decide whether to retrieve again or generate. The docs' agentic RAG guide is the reference implementation. Not the
Sequential LLMChain-style pipelines become StateGraph nodes with typed state. Each chain step is a node, the state schema replaces the implicit dict passing, and conditional edges replace the branching logic people used to hide in callbacks
Fixes "[name] is not a valid tool, try one of [tool]" when a custom LangGraph tool is rejected at runtime. Use when built-in tools work but your custom function gets this error. Cause: tools registered in only one of the two places. Fix: pa
Shows how to handle ToolException inside a LangGraph agent so one bad tool call does not kill the run. Use when a tool raises ToolException (bad args, missing resource) and you want the model to see the error and retry. Pattern: catch it in
Shows how to resume a LangGraph stream after a custom human_assistance tool calls interrupt(). Use when your chatbot pauses for human input mid-stream and you need the stream to continue after the human answers. Requires a checkpointer; res
Explains LangGraph's interrupt_after semantics: it fires after the node AND its outgoing edges run. Use when interrupt_after seems to trigger at the wrong time or your conditional edge runs before the pause. Fixed by switching to interrupt_
Explains LangGraph's "Found edge starting at unknown node" validation error. Use when graph.compile() or validate() raises it. It means an edge references a node name that was never added, usually a typo. Fix the name; every edge source mus
Fixes LangGraph's AsyncPostgresSaver failing to read checkpoints with a NoneType error on version 2.0.23. Use when alist/get_tuple raises about NoneType not being a mapping on langgraph-checkpoint-postgres 2.0.23. Fixed in the next release;