FlowiseAI/Flowise · error · Error

Invalid Condition: ${exception}

Error message

Invalid Condition: ${exception}

What it means

Catch-all thrown by the Condition node's UI-grid evaluator (conditionUI branch). Any inner failure during condition evaluation — JSON.parse of the grid, customGet on a $flow/$vars path, checkCondition's type coercion, or casting messageOutput.content to string — is caught and re-thrown with the prefix 'Invalid Condition: ' plus the original exception. The wrapper preserves the root cause in its suffix, so read the appended text to find the real failure.

Source

Thrown at packages/components/nodes/sequentialagents/ConditionAgent/ConditionAgent.ts:595

                    }
                } 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: ConditionAgent_SeqAgents }

View on GitHub (pinned to abe4a8601a)

Solutions

1. Read the text appended after 'Invalid Condition: ' — it names the real error (SyntaxError for JSON, TypeError for a bad cast, etc.).
2. Validate the conditionUI JSON in a linter; confirm it is an array of {variable, operation, value, output} items.
3. For every item.variable starting with '$', confirm the referenced nodeId still exists and produced a message in state.messages.
4. If the upstream node emits array/object content, flatten it to a string before it reaches the comparison, or reference a $flow./$vars. scalar instead.

Example fix

// before: casts multi-part content to string, throws on .content being an array
if (checkCondition(messageOutput.content as string, item.operation, item.value)) { return item.output }

// after: normalize content to a string first
const raw = messageOutput.content
const text = typeof raw === 'string' ? raw : Array.isArray(raw) ? raw.map(p => typeof p === 'string' ? p : p?.text ?? '').join('') : String(raw ?? '')
if (checkCondition(text, item.operation, item.value)) { return item.output }

function validateConditionGrid(conditionUI: unknown): {variable:string;operation:string;value:any;output:string}[] {
  const items = typeof conditionUI === 'string' ? JSON.parse(conditionUI) : conditionUI
  if (!Array.isArray(items)) throw new Error('conditionUI must be an array')
  return items.map((it, i) => {
    if (!it || !it.variable) throw new Error(`Row ${i}: variable is required`)
    return it
  })
}

const isConditionItem = (x: any): x is {variable:string;operation:string;value:any;output:string} =>
  !!x && typeof x === 'object' && typeof x.variable === 'string' && typeof x.operation === 'string'

try {
  // evaluate condition grid
} catch (e) {
  // unwrap the 'Invalid Condition: <inner>' prefix to inspect the real cause
  const inner = String(e?.message ?? e).replace(/^Invalid Condition:\s*/, '')
  logger.error({ inner }, 'condition evaluation failed')
  throw e
}

When it happens

Trigger: The conditionUI value is a non-empty string that fails JSON.parse; a grid item.variable is undefined (caught by the explicit 'Condition variable is required!' check, then re-wrapped); a $nodeId reference points to a node that emitted no message so messageOutput is undefined and later coerced; checkCondition receives a content value that is an array/object (multi-part LLM content) cast with `as string`; an unsupported operation string reaches the switch in checkCondition.

Common situations: Editing the condition grid in the UI then deploying untested; renaming or deleting an upstream sequential node so a $nodeId reference dangles; an upstream LLM returning multimodal/array content that is no longer a plain string; hand-editing the exported chatflow JSON and corrupting the conditionUI array.

Related errors

• Condition must have a predecessor!
• Condition Agent must have a predecessor!
• Agent name is required!
• Agent must have a predecessor!
• Condition function must return a string

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/2080c791283f57e2. Report an issue: GitHub.