Error:

—–> Building on the Heroku-22 stack
—–> Determining which buildpack to use for this app
! No default language could be detected for this app.
HINT: This occurs when Heroku cannot detect the buildpack to use for this application automatically.
See https://devcenter.heroku.com/articles/buildpacks
! Push failed

My goal:

i have a github repo where i have frontend(React) and backend(Flask) with its DB(Mongo). my goal is to containerize the applications using docker and then deploy it on heroku. I have successfully containerized in docker. but when i try to deploy it on heroku, i get error.

my root directory looks like this