"Unexpected Token U In JSON At Position 0"

When I run the endpoint on Postman it works fine and returns the result it posted, but when I use TEST on AWS lambda it returns the error "Unexpected token u in JSON at position 0". I checked the Use Lambda proxy on API gateway inside integration request, would that effect something?

Here is my lambda function

'use strict';

const uuid = require('uuid');
const AWS = require('aws-sdk'); // eslint-disable-line import/no-extraneous-dependencies

const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports.create = (event, context, callback) => {
  const timestamp = new Date().getTime();
  const data = JSON.parse(event.body);

  if (typeof data.phoneNumber !== 'string') {
    console.error('Validation Failed');
    callback(null, {
      statusCode: 400,
      headers: { 'Content-Type': 'text/plain' },
      body: 'Couldn\'t create item.',
    });
    return;
  }

  const params = {
    TableName: process.env.DYNAMODB_TABLE,
    Item: {
      id: uuid.v1(),

      phoneNumber: data.phoneNumber,
      sub: data.sub,

      createdAt: timestamp,
      updatedAt: timestamp,
    },
  };

  console.log(params);

  // write the lakeSubscription to the database
  dynamoDb.put(params, (error) => {
    // handle potential errors

    if (error) {
      console.error(error);
      callback(null, {
        statusCode: error.statusCode || 501,
        headers: { 'Content-Type': 'text/plain' },
        body: 'Couldn\'t create in dynamoDb.',
      });
      return;
    }

    // create a response
    const response = {
      statusCode: 200,
      body: JSON.stringify(params.Item),
    };
    callback(null, response);
  });
};

First of all if you see the JSON that you have provided:

{ "phoneNumber": "+11231231234", "sub": [ { "Name": "Tillery" }, { "Name": "Bob" } ] }

There's no body key. You can just use event instead of event.body. Like

console.log(event);

The input from AWS test event is already JSON Object and you don't need to parse it again.

Please remove JSON.parse and you'll be good.

Thanks!