When I try to build my app on Heroku, it fails because the Ruby version I purportedly am using is not supported by Heroku. My app has no problem building/deploying locally. Here is full message log:
-----> Ruby app detected
-----> Compiling Ruby/Rails
Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/heroku-18/ruby-2.3.8.tgz -s -o - | tar zxf - ' failed on attempt 1 of 3.
Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/heroku-18/ruby-2.3.8.tgz -s -o - | tar zxf - ' failed on attempt 2 of 3.
!
! An error occurred while installing ruby-2.3.8
!
! This version of Ruby is not available on Heroku-18. The minimum supported version
! of Ruby on the Heroku-18 stack can found at:
!
! https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
!
! Push rejected, failed to compile Ruby app.
! Push failed
However, in my Gemfile and Gemfile.lock, I am NOT using ruby-2.3.8. That is why I am very confused. I have links to my Gemfile gist and Gemfile.lock gist.
Things I have tried on Heroku:
Running bundle install.
This. Did not resolve issue, my Gemfile, Gemfile.lock, and local Ruby is ALL 2.6.3.
Making sure Gemfile and Gemfile.lock are the most recent ones in my Github.
Running gem install bundler -v 1.17.3 but it gives me ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /var/lib/gems/2.5.0 directory
EDIT:
It appears after running heroku run ruby -v, that my Ruby version is actually ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux-gnu]