#Try git show-ref to see what refs you have. Is there a refs/heads/master?
#Due to the recent "Replacing master with main in GitHub" action,
#you may notice that there is a refs/heads/main. As a result,
#the following command may change
#from ---> git push origin HEAD:master
#to ---> git push origin HEAD:main
#You can try
git push origin HEAD:master
#as a more local-reference-independent solution. This explicitly states
#that you want to push the local ref HEAD to the remote ref master
#(see the git-push refspec documentation).