awscli elasticbeanstalk create-application-version failing

Following the instructions here: https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/environment-mgmt-compose.html. I am trying to create my application version. My env.yaml file looks like

EnvironmentName: webapp+
EnvironmentLinks:
  "PARSE_HOST" : "server+"
AWSConfigurationTemplateVersion: 1.1.0.0
EnvironmentTier: 
  Name: WebServer
  Type: Standard
SolutionStack: Node.js 18 running on 64bit Amazon Linux 2023/6.0.0

I execute the create-application-version command and I get a response that looks like

{
    "ApplicationVersion": {
        "ApplicationVersionArn": "arn:aws:elasticbeanstalk:us-east-1:785468206857:applicationversion/MyApp/my-ap
p-v1",
        "ApplicationName": "MyApp",
        "VersionLabel": "my-app-v1",
        "SourceBundle": {
            "S3Bucket": "myapp",
            "S3Key": "myapp-dev-src-bundles/myapp-app-dev.zip"
        },
        "DateCreated": "2023-09-09T16:03:26.782000+00:00",
        "DateUpdated": "2023-09-09T16:03:26.782000+00:00",
        "Status": "PROCESSING"
    }
}

And my application version shows up in the console. Then I query the version to make sure it is done using aws elasticbeanstalk describe-application-versions --application-name MyApp I get the following response:

{
    "ApplicationVersions": [
        {
            "ApplicationVersionArn": "arn:aws:elasticbeanstalk:us-east-1:785468206857:applicationversion/MyApp/myapp-app-v1",
            "ApplicationName": "MyApp",
            "VersionLabel": myapp-app-v1",
            "SourceBundle": {
                "S3Bucket": "myapp",
                "S3Key": "myapp-dev-src-bundles/myapp-app-dev.zip"
            },
            "DateCreated": "2023-09-09T16:03:26.782000+00:00",
            "DateUpdated": "2023-09-09T16:03:26.782000+00:00",
            "Status": "FAILED"
        }
    ]
}

How do I find out why it is failing?