FlowiseAI/Flowise · error · Error

Condition variable is required!

Error message

Condition variable is required!

What it means

On the `conditionUI` grid branch, each row is evaluated by reading its `variable`, `operation`, and `value`. The first check inside the loop is `if (!item.variable)` — a row with no variable cannot be evaluated at all, so the loop aborts immediately.

Source

Thrown at packages/components/nodes/sequentialagents/Condition/Condition.ts:297

    }

    if (selectedTab === 'conditionFunction' && conditionFunction) {
        const sandbox = createCodeExecutionSandbox(input, variables, flow)

        try {
            const response = await executeJavaScriptCode(conditionFunction, sandbox)

            if (typeof response !== 'string') throw new Error('Condition function must return a string')
            return response
        } catch (e) {
            throw new Error(e)
        }
    } else if (selectedTab === 'conditionUI' && conditionUI) {
        try {
            const conditionItems: IConditionGridItem[] = typeof conditionUI === 'string' ? JSON.parse(conditionUI) : conditionUI

            for (const item of conditionItems) {
                if (!item.variable) throw new Error('Condition variable is required!')

                if (item.variable.startsWith('$flow')) {
                    const variableValue = customGet(flow, item.variable.replace('$flow.', ''))
                    if (checkCondition(variableValue, item.operation, item.value)) {
                        return item.output
                    }
                } else if (item.variable.startsWith('$vars')) {
                    const variableValue = customGet(flow, item.variable.replace('$', ''))
                    if (checkCondition(variableValue, item.operation, item.value)) {
                        return item.output
                    }
                } 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]

View on GitHub (pinned to abe4a8601a)

Solutions

1. Set a non-empty variable (e.g. `$flow.state.x` or `$vars.y`) for every row in the conditionUI grid.
2. Remove empty/incomplete rows before saving.
3. Use the visual picker rather than editing raw JSON so the field is enforced.

Example fix

// before
conditionUI = '[{"operation":">","value":"18"}]' // throws [293]

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

function validateConditionGrid(items) {
  const arr = typeof items === 'string' ? JSON.parse(items) : items
  for (const [i, item] of arr.entries()) {
    if (!item.variable) throw new Error(`Condition row ${i} is missing a 'variable'`)
  }
  return arr
}

validateConditionGrid(nodeData.inputs.conditionUI)

function isConditionGridItem(v): v is IConditionGridItem {
  return v != null && typeof v === 'object' && typeof (v as any).variable === 'string' && (v as any).variable.length > 0
}

When it happens

Trigger: Saving the conditionUI grid with one or more rows where the `variable` field is empty or missing.

Common situations: User added a condition row but did not pick a variable from the dropdown; duplicated a row and cleared the variable; edited the grid JSON directly and omitted `variable`.

Related errors

• Condition variable is required!
• Invalid JSON in the Agent's Prompt Input Values: ${exception
• Agent input variables values are not provided!
• Key is required
• Condition function must return a string

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/91acf4ad104c6fde. Report an issue: GitHub.