ScrapeGraphAI/Scrapegraph-ai · error · ValueError

Error evaluating condition '{condition}' in {self.node_name}

Error message

Error evaluating condition '{condition}' in {self.node_name}: {e}

What it means

ConditionalNode._evaluate_condition uses asteval to safely evaluate the configured condition expression against the state; any exception during evaluation (unknown state variable, type error, unsupported operator, bad syntax) is wrapped in this ValueError that includes the node name and original error.

Source

Thrown at scrapegraphai/nodes/conditional_node.py:110

            condition (str): The condition expression to evaluate.

        Returns:
            bool: The result of the condition evaluation.
        """
        # Combine state and allowed functions for evaluation context
        eval_globals = self.eval_instance.functions.copy()
        eval_globals.update(state)

        try:
            result = simple_eval(
                condition,
                names=eval_globals,
                functions=self.eval_instance.functions,
                operators=self.eval_instance.operators,
            )
            return bool(result)
        except Exception as e:
            raise ValueError(
                f"Error evaluating condition '{condition}' in {self.node_name}: {e}"
            )

View on GitHub (pinned to 532dfffbf6)

Solutions

1. Read the embedded '{e}' message to identify the underlying eval failure
2. Guard the condition against missing/None values, e.g. "parsed_docs is not None and len(parsed_docs) > 0"
3. Keep conditions to simple comparisons/logic supported by asteval (no imports, comprehensions, or complex attribute chains)
4. Test the condition string with the actual state dict in isolation

Example fix

# before
condition = "len(parsed_docs) > 0"
# after
condition = "parsed_docs is not None and len(parsed_docs) > 0"

# dry-run the condition against a sample state before deploying
from asteval import Interpreter
interp = Interpreter()
interp.symtable.update(sample_state)
assert interp(condition_expr) is not None or True  # smoke test

try:
    nxt = node.execute(state)
except ValueError as e:
    if 'Error evaluating condition' in str(e):
        logger.warning('condition failed; defaulting to false branch')
        nxt = node.false_node_name
    else:
        raise

When it happens

Trigger: A condition referencing a state key that is absent (NameError in eval), comparing incompatible types (e.g. 'len(parsed_docs) > "3"'), or using Python features asteval does not support (comprehensions, attribute access restrictions).

Common situations: Writing conditions against state keys that may be None on some paths; conditions that assume a type (list/int) the state doesn't hold for a given run; asteval's restricted eval rejecting a valid-Python expression.

Related errors

• You need to provide key_name inside the node config
• ConditionalNode's next nodes are not set properly.
• ConditionalNode '{node.node_name}' must have exactly two out
• Failed to set false_node_name for ConditionalNode '{node.nod
• Conditional Node returned a node name '{result}' that does n

AI-assisted analysis of ScrapeGraphAI/Scrapegraph-ai@532dfffbf6 (2026-08-28). Data as JSON: /api/errors/b03c80729cdb6863. Report an issue: GitHub.