Aws lambda aws注册无效AmbdareSponseException

我在注册用户时遇到此错误：

调用注册操作时发生错误（InvalidLambdaResponseException）：无法识别的lambda输出

我的代码：

from __future__ import print_function
import json
import boto3
import botocore.exceptions
import hmac
import hashlib
import base64
import json
import uuid


client = None

USER_POOL_ID = 'us-east-2_ssqaX****';
CLIENT_ID = '40kq19dp3tgaost148115****';
CLIENT_SECRET = '1rbns01jnv2ckiu1so8ntqjt8l6r****lgq2a4hni642s*****';



ERROR = 0
SUCCESS = 1
USER_EXISTS = 2


def get_secret_hash(username):
msg = username + CLIENT_ID
dig = hmac.new(str(CLIENT_SECRET).encode('utf-8'), 
    msg = str(msg).encode('utf-8'), digestmod=hashlib.sha256).digest()
d2 = base64.b64encode(dig).decode()
print("here" + d2)
return d2




def lambda_handler(event, context):

global client
if client == None:
    client = boto3.client('cognito-idp')

body = event
username = body['username']
password = body['password']

resp = client.sign_up(
ClientId=CLIENT_ID,
SecretHash=get_secret_hash(username),
Username=username,
Password=password
)

return {"resp": resp}

---

调用注册操作时发生错误（InvalidLambdaResponseException）：无法识别的lambda输出：InvalidLambdaResponseException

CloudWatch日志中有什么？你的Lambda代码在哪？我编辑过。。。发布了完整的代码。