Answers for "! [remote rejected] master -> master (non-fast forward)"

[rejected] main -> main (non-fast-forward)

git pull --rebase         this will solve the issue

rejected master -> master (non-fast-forward)

# if you updated your files on github.com so may be thats its asking first pull
# request then your push the request.
# so Very simple first:
# not use -f 
git pull origin master
# then
git push origin master