ScrapeGraphAI/Scrapegraph-ai · error · ValueError

Failed to set false_node_name for ConditionalNode '{node.nod

Error message

Failed to set false_node_name for ConditionalNode '{node.node_name}'

What it means

Companion check in _set_conditional_node_edges: after confirming two outgoing edges exist, reading outgoing_edges[1][1].node_name failed with IndexError or AttributeError. In practice this fires when the second edge's to_node is None or an object without a node_name attribute (e.g. a malformed tuple in the edges list).

Source

Thrown at scrapegraphai/graphs/base_graph.py:122

        for node in self.nodes:
            if node.node_type == "conditional_node":
                outgoing_edges = [
                    (from_node, to_node)
                    for from_node, to_node in self.raw_edges
                    if from_node.node_name == node.node_name
                ]
                if len(outgoing_edges) != 2:
                    raise ValueError(
                        f"ConditionalNode '{node.node_name}' must have exactly two outgoing edges."
                    )
                node.true_node_name = outgoing_edges[0][1].node_name
                try:
                    node.false_node_name = outgoing_edges[1][1].node_name
                except (IndexError, AttributeError) as e:
                    # IndexError: If outgoing_edges[1] doesn't exist
                    # AttributeError: If to_node is None or doesn't have node_name
                    node.false_node_name = None
                    raise ValueError(
                        f"Failed to set false_node_name for ConditionalNode '{node.node_name}'"
                    ) from e

    def _get_node_by_name(self, node_name: str):
        """Returns a node instance by its name."""
        return next(node for node in self.nodes if node.node_name == node_name)

    def _update_source_info(self, current_node, state):
        """Updates source type and source information from FetchNode."""
        source_type = None
        source = []
        prompt = None

        if current_node.__class__.__name__ == "FetchNode":
            source_type = list(state.keys())[1]
            if state.get("user_prompt", None):
                prompt = (
                    state["user_prompt"]

View on GitHub (pinned to 532dfffbf6)

Solutions

  1. Inspect the raw_edges/edges list and make sure every tuple's second element is a fully constructed BaseNode with a node_name.
  2. Fix the code that produced a None destination (usually a node-lookup miss) so it returns the real node instance.
  3. Add an assertion when building edges: assert to_node is not None and hasattr(to_node, 'node_name').

Example fix

# before
edges = [(cond, node_a), (cond, nodes_by_name.get('missing'))]

# after
edges = [(cond, node_a), (cond, nodes_by_name['fallback_node'])]
Defensive patterns

Strategy: validation

Validate before calling

for f, t in edges:
    assert t is not None and hasattr(t, 'node_name'), f'malformed edge destination: {t!r}'

Type guard

def edges_well_formed(edges) -> bool:
    return all(t is not None and hasattr(t, 'node_name') for _, t in edges)

Try / catch

try:
    g = BaseGraph(nodes=nodes, edges=edges, entry_point=entry)
except ValueError as e:
    if 'false_node_name' in str(e):
        # inspect edges for None/malformed second destination, fix, retry
        raise
    raise

Prevention

When it happens

Trigger: Passing an edge tuple whose destination is None ([(cond, real_node), (cond, None)]) or a non-node object (string, dict) in the second position; a node whose node_name attribute was deleted or never set.

Common situations: Programmatically building edge lists where a lookup of a node by name returned None; typos when constructing tuples; partially initialized node objects in test fixtures.

Related errors

AI-assisted analysis of ScrapeGraphAI/Scrapegraph-ai@532dfffbf6 (2026-08-28). Data as JSON: /api/errors/c5efcddcaa46d409. Report an issue: GitHub.