You need to create an extension file server_cert_ext.cnf with the content below. This extension file is required in the 3rd step of the batch script for configuring the self-signed certificate as an end-entity certificate by setting the CA (Certificate Authority) parameter to false.
Content of extension file server_cert_ext.cnf:
basicConstraints = CA:FALSE
The following commands must be executed in the directory of the server_cert_ext.cnf file: