[Solved] Why does this LangGraph flow raise an error?flow.add_node(HumanNode(name='validate')) flow.add_node(AINode(name='process')) result = flow.run() | LangChain

LangChain - LangGraph for Stateful Agents

Why does this LangGraph flow raise an error?

flow.add_node(HumanNode(name='validate'))
flow.add_node(AINode(name='process'))
result = flow.run()

ANo edge connects 'validate' to 'process', so data flow is incomplete

BHumanNode cannot be added before an AINode

CThe run method requires an input argument

DAINode must be added before HumanNode

Step-by-Step Solution

Solution:

Step 1: Check node connections
Nodes must be connected with edges to define data flow.
Step 2: Identify missing connection
Here, no edge connects 'validate' to 'process', causing runtime failure.
Final Answer:
No edge connects 'validate' to 'process', so data flow is incomplete -> Option A
Quick Check:
Edges are required between nodes [OK]

Quick Trick: Always connect nodes with edges before running flow [OK]

Common Mistakes:

MISTAKES

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