I wanted to convert my AWS Elastic Beanstalk instance from using t1.micro to t2.micro since the t2.micro instances cost less and are now the recommended way to use Elastic Beanstalk. However, if you simply just change the instance type to t2.micro, the instance environment will change to a red error state and you will get the following error message:
Launching a new EC2 instance. Status Reason: The specified instance type can only be used in a VPC. A subnet ID or network interface ID is required to carry out the request. Launching EC2 instance failed.
Overcoming this error and switching to t2.micro is not difficult, but it also is not obvious how to do it. The following instructions show how. Continue reading Migrate AWS Elastic Beanstalk from t1.micro to t2.micro