Bundler 找不到 gem“ruby”的兼容版本

Question

I was trying to bundle install , but I keep on getting this error message.

My attempt was to update the version of ruby. However, this did not work. I also researched the compatible version of activerecord that corresponds to ruby version 2.2.5., but I was not able to find any.
I would truly appreciate it if you could resolve this error.

Here below is my gemfile for reference:

ruby '2.2.5'
source 'https://rubygems.org'

gem 'sinatra', '~> 2.1'
gem 'sinatra-contrib', '~> 2.1'
gem 'webrick', '~> 1.7'
gem 'sinatra-activerecord', '~> 2.0'
gem 'activerecord', '~> 6.1'
gem 'pg', '~> 1.2'
gem 'rake', '~> 13.0'
gem 'bcrypt'
gem 'sinatra-flash'

group :development do
  gem 'debase'
  gem 'fastri'
  gem 'rcodetools'
  gem 'rubocop'
  gem 'ruby-debug-ide'
end

Answer 1

Reinstalling updated ruby version worked:

rvm reinstall ruby-2.6.3

bundle install