如何在项目中更新Rails的版本？ Bundler找不到宝石“ activemodel”的兼容版本

Question

I don't understand the problem. Bundler says it needs activemodel >= 4.2.0, >= 4.0, and = 5.2.1.rc1. So why doesn't it just pick 5.2.1.rc1 because that satisfies all the dependencies?

There are dozens of errors like that for the gems rails , railties , etc.

I'm upgrading from Rails 4.2 to latest Rails. I commented out all version specifiers except Ruby and Rails. Here is my entire Gemfile .

workspace\>bundle
Fetching gem metadata from https://rubygems.org/..............
Fetching gem metadata from https://rubygems.org/..
You have requested:
  rails ~> 5.2

The bundle currently has rails locked at 4.2.3.
Try running `bundle update rails`

If you are updating multiple gems in your Gemfile at once,
try passing them all to `bundle update`

C:\Users\Chloe\workspace\>bundle update rails
Fetching gem metadata from https://rubygems.org/..............
Fetching gem metadata from https://rubygems.org/..
Resolving dependencies........
Bundler could not find compatible versions for gem "activemodel":
  In Gemfile:
    paperclip (~> 5.0) x64-mingw32 was resolved to 5.0.0, which depends on
      activemodel (>= 4.2.0) x64-mingw32

    rails (~> 5.2) x64-mingw32 was resolved to 5.2.1.rc1, which depends on
      activemodel (= 5.2.1.rc1) x64-mingw32

    web-console (~> 2.0) x64-mingw32 was resolved to 2.3.0, which depends on
      activemodel (>= 4.0) x64-mingw32

Answer 1

首先备份您的Gemfile.lock ，然后将其删除并尝试再次进行bundle install 。