javascript - Cannot push project to Heroku "no default language detected" -

i trying push project heroku , receiving error "no default language detected". project built on node , structure follows:

project/   .gitignore   procfile   server/     package.json     index.js     ...etc 

in procfile (since package.json not located in project root) have following line of code:

procfile:

web: node index.js

i pushing running: git push heroku master

where error "no default language detected" , despite best google/so searching efforts, cannot find proper solution past this. missing here?

your package.json must in root directory.
can change structure of project or try push subdirectory of project running: git subtree push --prefix server heroku master