Failed to parse data from executor - Zod validation error: "Expected object, received string" when triggering Inngest events

[inioluwa-io]

Describe the bug
When triggering an Inngest event, the function execution fails with a Zod validation error stating "Expected object, received string". The error occurs during the parseFnData step in the Inngest communication handler.

To Reproduce
Steps to reproduce the behavior:

1. Set up Next.js application with Inngest integration
2. Create and register Inngest functions
3. Trigger an Inngest event (either manually or programmatically)
4. Function execution fails with parsing error

Expected behavior
Inngest events should trigger successfully and functions should execute without parsing errors.

Screenshots / Stack trace dump

Failed to parse data from executor.
    at prettyError (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/helpers/errors.js:303:29)
    at parseFailureErr (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/helpers/functions.js:238:40)
    at parseFnData (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/helpers/functions.js:178:25)
    at InngestCommHandler.runStep (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/components/InngestCommHandler.js:864:64)
    at InngestCommHandler.handleAction (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/components/InngestCommHandler.js:642:50)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async ServerTiming.wrap (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/helpers/ServerTiming.js:64:21)
    at async ServerTiming.wrap (/Users/inioluwa/Code/kikin-finance/node_modules/inngest/helpers/ServerTiming.js:64:21)
    at async /Users/inioluwa/Code/kikin-finance/node_modules/@sentry/nextjs/cjs/server/wrapApiHandlerWithSentry.js:144:33

[
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "string",
    "path": [],
    "message": "Expected object, received string"
  }
] Function execution can't continue.

Make sure that your API is set up to parse incoming request bodies as JSON, like body-parser for Express (https://expressjs.com/en/resources/middleware/body-parser.html).

System info

• inngest version: 3.22.13
• Next.js version: 13.4.1
• Node.js version: v22.13.0
• OS: macOS 15.5 (24F74)

Additional context
The error suggests that the Inngest library is receiving a string when it expects an object during the parsing phase. This could be related to how the request body is being processed in the Next.js API route or how the data is being serialized/deserialized between the Inngest dashboard and the application.

[linear]

INN-5197 Failed to parse data from executor - Zod validation error: "Expected object, received string" when triggering Inngest events

[linear]

INN-5197 Failed to parse data from executor - Zod validation error: "Expected object, received string" when triggering Inngest events

[jpwilliams]

Hi @inioluwa-io 👋

Do you have the event you're sending to trigger the function?

Internally we should be using req.json().

inngest-js/packages/inngest/src/next.ts

Line 123 in f8a4a87

body: () => (typeof req.json === "function" ? req.json() : req.body),

[inioluwa-io]

Hi @inioluwa-io 👋

Do you have the event you're sending to trigger the function?

Internally we should be using req.json().

inngest-js/packages/inngest/src/next.ts

Line 123 in f8a4a87

body: () => (typeof req.json === "function" ? req.json() : req.body),

Hi @jpwilliams
This is the payload of the event

{
  "name": "xothic-underwriting-report-provider/report.requested",
  "data": {
    "BREGrade": null,
    "clarifyingQuestions": [],
    "companyId": "random_id",
    "confidence": null,
    "requestedBy": "email@gmail.com",
    "status": "PROCESSING",
    "updatedAt": "2025-06-24T10:46:20.739Z"
  },
  "user": {
        "email": "email@gmail.iocom
    }
  },
  "id": "01JYGRQGT9PH55JDEH0S9FBKY7",
  "ts": 1750761980745
}

[jpwilliams]

Looks good. Is this when using the Inngest Dev Server or in Cloud?

A quick log before parsing the data within node_modules/ might give us an immediate direction. 🙂

[inioluwa-io]

Yes, this is using the dev server.

This a log in InngestCommHandler.runStep right before the parsing.

 message {
  functionId: 'kikin-app-handle-xothic-underwriting-report-requested',
  stepId: 'step',
  data: '',
  timer: ServerTiming {
    timings: { handler: [Object], action: [Object], res: [Object] }
  },
}

Right inside InngestCommHandler.createHandler in the logic to get the body I logged these out as well

method: POST
contentLength: undefined

Is there other specific places you would suggest to log as well?

[inioluwa-io]

@jpwilliams I was able to get it to work by upgrading my Next.js version to 13.4.19. There was a section in the Inngest code which explicitly returns body as string if no content-length is available in the headers. Seems like next@13.4.1 removes the content-length.
Thank you for your help 🙂