Just moved my app to Heroku from *.meteor.com and can’t get it to work with Facebook auth. Still works fine locally. I create a new test app in FB to be safe.
It’s a problem of ROOT_URL
If you set ROOT_URL to myfooapp.com instead of myfooapp.herokuapp.com
It will solve your this problem and let users login with facebook from myfooapp.com
"BUT"
Using this will not let you login with Facebook, google or whatever with myfooapp.herokuapp.com