Ruby On Rails: bundle update: bundler can't resolve dependencies that seem to be resolvable

Question

As part of Rails upgrade I ran bundle update rails. I am a little confused by the output.

Bundler could not find compatible versions for gem "activemodel":
  In Gemfile:
    mongoid was resolved to 6.1.1, which depends on
      activemodel (~> 5.0)

    rails (= 5.0.7.2) was resolved to 5.0.7.2, which depends on
      activemodel (= 5.0.7.2)

Doesn't 5.0.7.2 satisfy (~> 5.0)?

Similarly:

Bundler could not find compatible versions for gem "rails":
  In Gemfile:
    rails (= 5.0.7.2)

    minitest-spec-rails was resolved to 5.5.0, which depends on
      rails (>= 4.1)

In this case too: 5.0.7.2 should satisfy rails (>= 4.1).

I am unsure of what I am missing here. Any help would be very much so appreciated.

Answer 1

rails upgrade might be a mess... you can try by adding each gem to the "bundle update" call... When I was updating from 5.0.7.2 to 6.1.6 I ended up with this...

bundle update bootstrap-kaminari-views devise_lastseenable leather simple_calendar where_exists rspec-expectations rspec-rails prawnto_2 validates_overlap slim-rails active_model_serializers grape-active_model_serializers jbuilder has_scope spring-commands-rspec pluck_to_hash tracking_number kaminari font-awesome-sass sinatra spring devise_masquerade

so, you can start by doing

bundle update mongoid rails

Also, you might need to check which versions of your gems are compatible with the rails version you want to install, so you might have to "lock" some gems to a certain version in order to the update to succeed