Rails: "Could not find bundler" (2.2.11) required by Gemfile.lock. (Gem::GemNotFoundException)

When I try to do bundler update I get this error:

.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:247:in
`to_specs': Could not find bundler (>= 0) amongst
[rake-0.8.7, rake-0.8.7, rubygems-update-1.8.4] (Gem::LoadError)

I'm new to Ruby, can someone tell me what would cause this? Rake 0.8.7 is installed.

Make sure you're entering "bundle" update, if you have the bundler gem installed.

bundle update

If you don't have bundler installed, do gem install bundler.

I had this problem, then I did:

gem install bundler

then in your project folder do:

bundle install

and then you can run your project using:

bundle exec rails server