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
I had the same error message output when trying to start an application within a Vagrant environment. It cropped up out of nowhere after zero changes to the application code (and other weird behaviour followed, such as development.rb being deleted upon attempting to run the app).
In the end I simply halted the VM & restarted it, everything was then fine so I'm assuming it was an issue with file syncing / shared folders perhaps? (default Vagrant shared folder being used).