Push rejected, Could not communicate with vendor, please try again later

[STRd6]

I get the following error when attempting to deploy:

       Done installing smart packages
       Building meteor bundle
       compileJade: updating npm dependencies -- jade, markdown...
Setting up MONGO_URL in .profile.d
-----> Vendoring node into slug
-----> Discovering process types
       Procfile declares types      -> (none)
       Default types for Meteor app -> web

-----> Compressing... done, 34.6MB
-----> Launching... 
 !     Push rejected, Could not communicate with vendor, please try again later

I believe that I followed the readme correctly. Any ideas?