GRAPH_RECURSION_LIMIT: infinite loop in the graph or a legitimately deep run

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GRAPHRECURSIONLIMIT

Diagnose first

Ask: should this graph terminate in a handful of steps? If yes, you have a cycle. The classic shape is two nodes with edges in both directions and a conditional edge whose condition never flips.

builder.add_edge("a", "b")
builder.add_edge("b", "a")  # where is the exit?

Fix

• Cycle: fix the conditional logic so some path reaches END.
• Legitimately deep: raise the limit per invocation:

graph.invoke({...}, {"recursion_limit": 1000})

Rules

• Do not raise the limit to silence a real infinite loop. A loop that burns 1000 steps burns money and time; fix the logic.
• In JS this is the GRAPHRECURSIONLIMIT error code on lc_error_code.
• Agent loops that call tools forever usually mean the model never gets a usable tool result; check the tool outputs, not just the graph.

Error catalog entry grounded in the official GRAPHRECURSIONLIMIT error page, verified 2026-09-26. Error page: https://docs.langchain.com/oss/python/langgraph/errors/GRAPHRECURSIONLIMIT