Hey @codingecho, a number of us are using Ubuntu 18.04 for building and haven’t experienced these errors. Have you tried a fresh checkout in a clean workspace, or in a new Ubuntu virtual machine?
There are also non-official docker containers to build balenaOS in Docker, like GitHub - alexgg/docker-balena: A balena OS docker image builder. It’s not well documented as we are planning to improve the build process with containers in future releases of balenaOS.