windmill-labs/windmill · error

Invalid

Error message

Invalid ${fieldName}: ${error?.message ?? 'unknown error'}

What it means

validateOptionalFlowModule parses a preprocessor_module or failure_module through the generated flowModuleSchema (zod) and throws the first zod issue's message wrapped as `Invalid <fieldName>: ...` when the module doesn't conform. This validates special optional modules in the copilot's editable flow JSON against the same schema used for regular flow modules.

Solutions

1. Read the zod issue message after 'Invalid <fieldName>:' — it names the exact path and expected type.
2. Fix the module so it conforms to flowModuleSchema (correct `id`, a valid `value` with a supported `type`, required fields present).
3. Validate the module locally with the same zod schema before calling the tool to catch all issues at once.

Example fix

// before
{"preprocessor_module":{"id":"prep"}}
// after
{"preprocessor_module":{"id":"prep","value":{"type":"rawscript","language":"python3","content":"print('hi')"}}}

import { flowModuleSchema } from './openFlowZod.gen'
const r = flowModuleSchema.safeParse(rawModule)
if (!r.success) {
  console.error(r.error.issues.map(i => `${i.path.join('.')}: ${i.message}`).join('; '))
}

function isFlowModule(v) {
  return flowModuleSchema.safeParse(v).success
}

try {
  validateEditableFlowJson(flow)
} catch (e) {
  const m = /^(Invalid (preprocessor_module|failure_module): )(.*)$/.exec(String(e.message))
  if (m) {
    // m[3] is the zod issue message; fix that path and retry
  } else throw e
}

When it happens

Trigger: Calling flowTools modules/patches where preprocessor_module or failure_module is present but fails flowModuleSchema — e.g. missing `id`, an unknown `value.type`, a wrong-typed `value`, or missing required fields like `input_transforms`.

Common situations: An LLM writes a failure module without a `value.type`; a hand-edited module omits required fields; a module shape copied from an older Windmill version no longer matches the generated schema.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Flow modules must be an array
• Invalid failure_module: id must be
• Invalid :\n
• Invalid flow modules:\n
• Invalid flow setting

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/88095d4445b83e53. Report an issue: GitHub.

Appendix: source

Thrown at frontend/src/lib/components/copilot/chat/flow/editableFlowJson.ts:316

	return parsedModules
}

export function validateFlowSchema(rawSchema: unknown): Record<string, any> | null {
	if (rawSchema == null) return null
	if (typeof rawSchema !== 'object' || Array.isArray(rawSchema)) {
		throw new Error('Flow schema must be an object or null')
	}
	return rawSchema as Record<string, any>
}

function validateOptionalFlowModule(rawModule: unknown, fieldName: string): FlowModule | null {
	if (rawModule == null) return null

	const result = flowModuleSchema.safeParse(rawModule)
	if (!result.success) {
		const error = result.error.issues[0]
		throw new Error(`Invalid ${fieldName}: ${error?.message ?? 'unknown error'}`)
	}
	return result.data
}

export const EDITABLE_FLOW_STRUCTURAL_KEYS = [
	'modules',
	'schema',
	'preprocessor_module',
	'failure_module',
	'groups',
	'notes'
] as const

/**
 * Parse and validate a raw object as an `EditableFlowJson`. Validates module
 * shape, schema shape, optional special modules (with their reserved ids),
 * groups, top-level flow settings, and that no module ids collide.
 */

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