FlowiseAI/Flowise · error · Error

Invalid Condition: ${exception}

Error message

Invalid Condition: ${exception}

What it means

A catch-all wrapper around the `conditionUI` evaluation branch. Any exception thrown while parsing the conditionUI JSON, resolving `$flow`/`$vars` references via `customGet`, or indexing into `messageOutputs` is re-thrown with the `Invalid Condition:` prefix and the original exception appended.

Source

Thrown at packages/components/nodes/sequentialagents/Condition/Condition.ts:326

                    }
                } else if (item.variable.startsWith('$')) {
                    const nodeId = item.variable.replace('$', '')

                    const messageOutputs = ((state.messages as unknown as BaseMessage[]) ?? []).filter(
                        (message) => message.additional_kwargs && message.additional_kwargs?.nodeId === nodeId
                    )
                    const messageOutput = messageOutputs[messageOutputs.length - 1]

                    if (messageOutput) {
                        if (checkCondition(messageOutput.content as string, item.operation, item.value)) {
                            return item.output
                        }
                    }
                }
            }
            return 'End'
        } catch (exception) {
            throw new Error('Invalid Condition: ' + exception)
        }
    }
}

module.exports = { nodeClass: Condition_SeqAgents }

View on GitHub (pinned to abe4a8601a)

Solutions

1. Validate `conditionUI` with `JSON.parse` before saving — fix any syntax errors.
2. Ensure every `$flow.*` and `$vars.*` path referenced in condition rows actually exists at runtime.
3. Use the UI grid editor rather than raw JSON so structure stays valid.
4. Inspect the appended exception text — it pinpoints the failing row or path.

Example fix

// before
conditionUI = '[{"variable":"$flow.state.age","operation":">","value":"18","output":"Approved"},]' // trailing comma -> throws [294]

// after
conditionUI = '[{"variable":"$flow.state.age","operation":">","value":"18","output":"Approved"}]'

function validateConditionUIStructure(raw) {
  const items = typeof raw === 'string' ? JSON.parse(raw) : raw
  if (!Array.isArray(items)) throw new Error('conditionUI must be a JSON array')
  for (const item of items) {
    if (!item.variable) throw new Error(`Row missing variable: ${JSON.stringify(item)}`)
  }
  return items
}

validateConditionUIStructure(nodeData.inputs.conditionUI)

function resolvesFlowPath(flow, path): boolean {
  const stripped = path.replace(/^\$flow\./, '')
  return customGet(flow, stripped) !== undefined
}

try {
  const branch = await runCondition(nodeData, input, options, state)
  return branch
} catch (e) {
  if (e?.message?.startsWith('Invalid Condition:')) {
    // log the wrapped cause and fall back to the default branch
    console.error('Condition eval failed, defaulting to End:', e.message)
    return 'End'
  }
  throw e
}

When it happens

Trigger: Malformed `conditionUI` JSON; a `$flow.x.y` path that does not exist (customGet returns undefined and downstream throws); accessing `messageOutputs[length-1]` when messages are not in the expected shape; an unsupported operation string.

Common situations: conditionUI was edited as raw JSON and broke syntax; the referenced `$flow.state.foo` path doesn't exist in the current graph; conversation history is empty so `messageOutputs` is empty; an `operation` was set that `checkCondition` does not handle.

Related errors

• Condition function must return a string
• Condition variable is required!
• Condition function must return a string
• Condition variable is required!
• Invalid Condition: ${exception}

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/7f55df671e93062b. Report an issue: GitHub.