Rails - "Required ruby-2.3.3 is not installed." after Ruby update to 2.5.3

Question

I have a Rails install where I updated the Ruby version from 2.3.3 to 2.5.3. I was previously using 2.3.3 from the Debian Ruby package, but installed 2.5.3 from RVM. I modified my Gemfile to use ruby '2.5.3' and ran bundle install. Rails is now using 2.5.3 as it should, but when I cd to the directory, I get a message:

Required ruby-2.3.3 is not installed. To install do: 'rvm install "ruby-2.3.3"'

I can't find where it's getting this. Running grep -r "2.3.3" * in my Rails project root returns nothing. I know it's something specific to this project, because I've cloned it over to another server and the message persists. What is reporting this and how do I tell it that 2.5.3 is the correct Ruby version?

Answer 1

.ruby-version

Also, if you had grepped with grep -r "2.3.3" . you would have found it.