I am trying to launch an EMR cluster using AWS Lambda code written with boto3 and python. The Lambda is able to launch the cluster when there is no VPC configuration associated it. However, as soon as I add the VPC config it fails to launch the cluster and errors out and does not provide any error message.

I am trying to launch the lambda inside a default VPC and it has 3 public subnets and a default security group. I have checked the route table in the VPC is associated with an internet gateway and it is attached to the VPC.

The execution role provides full access to the cloudwatch elasticmapreduce and ec2 actions.

Any help in resolving this school boy error will be much appreciated.