Custom email sender Lambda trigger in Amazon Cognito user pools throws errorMessage: Not a supported message format version.

I've followed the directions from this knowledge base article and tried testing the lambda, but I'm getting the error shown below.

https://repost.aws/en/knowledge-center/cognito-custom-email-sender-trigger

I'm using the same javascript code in the article and the similar request body to test the lambda. I've set the KEY_ALIAS and KEY_ARN environment variables to the appropriate values. Those are fake environment values below.

KEY_ALIAS = arn:aws:kms:us-east-1:asdfasdfadsf:alias/custom-email-key KEY_ARN = arn:aws:kms:us-east-1:adsfadfdsf:key/aadfadsfadsfadf1

**Can you tell me why it's giving me this error? I suspect the error is in the decrypt method. **

{
  "errorType": "Error",
  "errorMessage": "Not a supported message format version.",
  "trace": [
    "Error: Not a supported message format version.",
    "    at needs (/var/task/node_modules/@aws-crypto/material-management/build/main/src/needs.js:18:15)",
    "    at Object.deserializeMessageHeader (/var/task/node_modules/@aws-crypto/serialize/build/main/src/deserialize_factory.js:56:41)",
    "    at ParseHeaderStream._transform (/var/task/node_modules/@aws-crypto/decrypt-node/build/main/src/parse_header_stream.js:56:44)",
    "    at Transform._read (/var/task/node_modules/readable-stream/lib/_stream_transform.js:166:10)",
    "    at Transform._write (/var/task/node_modules/readable-stream/lib/_stream_transform.js:155:83)",
    "    at doWrite (/var/task/node_modules/readable-stream/lib/_stream_writable.js:390:139)",
    "    at writeOrBuffer (/var/task/node_modules/readable-stream/lib/_stream_writable.js:381:5)",
    "    at Writable.write (/var/task/node_modules/readable-stream/lib/_stream_writable.js:302:11)",
    "    at Duplexify._write (/var/task/node_modules/duplexify/index.js:212:22)",
    "    at doWrite (/var/task/node_modules/readable-stream/lib/_stream_writable.js:390:139)"
  ]
}

Request body (test event)

{
  "version": "1",
  "triggerSource": "CustomEmailSender_ForgotPassword",
  "region": "us-east-1",
  "userPoolId": "us-east-1sadfsdfsdf",
  "userName": "ertetrt-ertertet-x-ertertert-erertertert",
  "callerContext": {
    "awsSdkVersion": "aws-sdk-nodejs-2.856.0",
    "clientId": "sfsffsfsfdfdf"
  },
  "request": {
    "type": "customEmailSenderRequestV1",
    "code": "dGhpc2lzbXl0ZXN0OUxM",
    "clientMetadata": null,
    "userAttributes": {
      "sub": "ertetrt-ertertet-x-ertertert-erertertert",
      "email_verified": "true",
      "email": "test@gmail.com"
    }
  }
}