The value of '#' does not match schema definition

[kharikbo]

Hi everyone!

I have this code:

const app: FastifyInstance = fastify({
  ajv: {
    customOptions: {
      coerceTypes: 'array'
    },
  },
});

const schema = {
  body: {
    type: 'object',
    properties: {
      name: {
        type: 'string',
      },
    },
  },
}

// somethings

And and when i am emulating error (for example pass "name" with type integer") and It's coming back anyway:

it always return:

{"statusCode":500,"error":"Internal Server Error","message":"The value of '#' does not match schema definition."}

More details

TypeError: The value of '#' does not match schema definition.
at main (eval at build (/usr/src/app/node_modules/fast-json-stringify/index.js:175:23), <anonymous>:13:18)
at serialize (/usr/src/app/node_modules/fastify/lib/reply.js:879:12)
at preSerializationHookEnd (/usr/src/app/node_modules/fastify/lib/reply.js:510:17)
at preSerializationHook (/usr/src/app/node_modules/fastify/lib/reply.js:494:5)
at Reply.send (/usr/src/app/node_modules/fastify/lib/reply.js:197:7)
at /usr/src/app/node_modules/fastify/lib/wrapThenable.js:25:15
at processTicksAndRejections (node:internal/process/task_queues:95:5) {
serialization: { url: '/user/id/:id', method: 'GET' }
 }

although it should be
https://fastify.dev/docs/latest/Reference/Validation-and-Serialization/#error-handling

{
  "statusCode": 400,
  "error": "Bad Request",
  "message": "body should have required property 'name'"
}

---

What is value of "#"? and where is typical error message with 400 status code?

[Eomm]

The error happens during the serialization (see the logs: fast-json-stringify) and not during the request parsing.

Could you add a Minimal, Reproducible Example?

Without it, we are unable to help you.

[kharikbo]

My bad, I actually forgot to reply to you!

It's normal behavior for fast-json-stringify