rails server bin/rails:6: warning: already initialized constant APP_PATH error

Question

I\'ve tried a number of things like uninstalling/reinstalling rails and gems but to no avail.

When I go into my new project and run rails s or bundle exec rails serv

Answer 1

This happened to me after doing a brew upgrade. My guess is that this broke some gems with native extensions, even though there was no error message pointing to that.

What I ended up doing was completely removing my installed gems (In my case I completely uninstalled and reinstalled the ruby version using rbenv).
Running bundle install recompiled the native extensions, and everything was running again.

Answer 2

For me this issue presented as a result of bundle upgrading rvm-capistrano amongst other things.
Adding this require:false fixed things in the end as per this previous post

gem  'rvm-capistrano',  require: false

Although could possibly be an additional issue - as running rake rails:update:bin may have helped clear the initial issue.