ScrapeGraphAI/Scrapegraph-ai · error · ValueError

Node with name '{node.node_name}' already exists in the grap

Error message

Node with name '{node.node_name}' already exists in the graph.
             You can change it by setting the 'node_name' attribute.

What it means

BaseGraph.append_node refuses to add a node whose node_name already exists among the graph's nodes, because routing (edges dict keyed by node_name) and conditional-node resolution rely on unique names. The message suggests overriding the node_name attribute.

Source

Thrown at scrapegraphai/graphs/base_graph.py:388

            logger.info(state["generated_code"])
        elif "merged_script" in state:
            logger.info(state["merged_script"])

        logger.info("✨ Try enhanced version of ScrapegraphAI at %s ✨", CLICKABLE_URL)

        return state, exec_info

    def append_node(self, node):
        """
        Adds a node to the graph.

        Args:
            node (BaseNode): The node instance to add to the graph.
        """

        # if node name already exists in the graph, raise an exception
        if node.node_name in {n.node_name for n in self.nodes}:
            raise ValueError(
                f"""Node with name '{node.node_name}' already exists in the graph.
                             You can change it by setting the 'node_name' attribute."""
            )

        last_node = self.nodes[-1]
        self.raw_edges.append((last_node, node))
        self.nodes.append(node)
        self.edges = self._create_edges(set(self.raw_edges))

View on GitHub (pinned to 532dfffbf6)

Solutions

Give the new node a unique name via its constructor: FetchNode(node_name='fetch_retry', ...).
Skip the append if the name already exists (check {n.node_name for n in graph.nodes} first) when the node is intentionally identical.
Reuse the existing node instance instead of appending a duplicate.

Example fix

# before
graph.append_node(FetchNode(node_config=cfg))
graph.append_node(FetchNode(node_config=cfg))  # duplicate default name 'fetch'

# after
graph.append_node(FetchNode(node_config=cfg))
graph.append_node(FetchNode(node_name='fetch_second', node_config=cfg))

Defensive patterns

Strategy: validation

Validate before calling

existing = {n.node_name for n in graph.nodes}
if node.node_name in existing:
    node.node_name = f'{node.node_name}_{len(existing)}'  # or skip
graph.append_node(node)

Type guard

def name_is_unique(node, graph) -> bool:
    return node.node_name not in {n.node_name for n in graph.nodes}

Try / catch

try:
    graph.append_node(node)
except ValueError as e:
    if 'already exists' in str(e):
        node.node_name += '_2'
        graph.append_node(node)
    else:
        raise

Prevention

Pass explicit node_name when appending same-class nodes.
Check the node-name set before appending in loops.
Prefer reusing existing instances over appending duplicates.

When it happens

Trigger: Calling graph.append_node(FetchNode(...)) twice, or appending two nodes of the same class with default names (both default to e.g. 'fetch'); appending a node whose node_name was manually set to an existing one.

Common situations: Building custom pipelines in a loop that instantiates the same node class repeatedly; copy-pasting node blocks without changing node_name; appending a second FetchNode for retry logic.

Related errors

AI-assisted analysis of ScrapeGraphAI/Scrapegraph-ai@532dfffbf6 (2026-08-28). Data as JSON: /api/errors/bfd02d8af6cf514b. Report an issue: GitHub.