`start-invalid-workflow-function`

This error occurs when you try to call start() with a function that is not a valid workflow function or when the Workflow DevKit is not configured correctly.

Error Message

'start' received an invalid workflow function. Ensure the Workflow DevKit
is configured correctly and the function includes a 'use workflow' directive.

The start() function expects a workflow function that has been properly processed by Workflow DevKit's build system. During the build process, workflow functions are transformed and marked with special metadata that start() uses to identify and execute them.

This error typically happens when:

The function is missing the "use workflow" directive
The workflow isn't being built/transformed correctly
The function isn't exported from the workflow file
The wrong function is being imported

Common Causes

Missing `"use workflow"` Directive

workflows/order.ts

// Error - missing directive
export async function processOrder(orderId: string) { 
  // workflow logic
  return { status: 'completed' };
}

Solution: Add the "use workflow" directive.

workflows/order.ts

// Fixed - includes directive
export async function processOrder(orderId: string) {
  "use workflow"; 

  // workflow logic
  return { status: 'completed' };
}

Incorrect Import

app/api/route.ts

import { start } from 'workflow/api';
// Error - importing step function instead of workflow
import { processStep } from '@/workflows/order'; 

export async function POST(request: Request) {
  await start(processStep, ['order-123']); // Error!
  return Response.json({ started: true });
}

Solution: Import the correct workflow function.

app/api/route.ts

import { start } from 'workflow/api';
// Fixed - import workflow function
import { processOrder } from '@/workflows/order'; 

export async function POST(request: Request) {
  await start(processOrder, ['order-123']); 
  return Response.json({ started: true });
}

Next.js Configuration Missing

next.config.ts

// Error - missing withWorkflow wrapper
import type { NextConfig } from 'next';

const nextConfig: NextConfig = {
  // your config
};

export default nextConfig;

Solution: Wrap with withWorkflow().