error: src refspec main does not match any error: failed to push some refs to 'https://git.heroku.com/mbot56.git' code example

Example 1: git push heroku master error: src refspec master does not match any error: failed to push some refs to 'https://git.heroku.com/write-any.git'

git push heroku HEAD:master

Example 2: error: src refspec main does not match any error: failed to push some refs to 'https://github.com/majeduli/paul-template.git'

error: src refspec master does not match any.  
error: failed to push some refs to 'ssh://xxxxx.com/project.git'