Heroku 由于可能的 Bundler 问题 (Rails 6.0) 推送失败

Question

我刚刚将我的应用程序升级到 Rails 6.0，现在无法推送到 Heroku。

我的推送显示此错误：

remote:  !     Push rejected, failed to compile Ruby app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !   Push rejected to aloop-staging.
remote: 

但是，如果我查看 Heroku 上的活动日志，它会显示：

-----> Installing node-v8.10.0-linux-x64
-----> Detecting rake tasks
 !
 !     Could not detect rake tasks
 !     ensure you can run `$ bundle exec rake -P` against your app
 !     and using the production group of your Gemfile.
 !     Activating bundler (2.0.2) failed:
 !     Could not find 'bundler' (2.0.2) required by your /tmp/build_c16174fa21307792629df435f91cd5ae/Gemfile.lock.
 !     To update to the latest version installed on your system, run `bundle update --bundler`.
 !     To install the missing version, run `gem install bundler:2.0.2`
 !     Checked in 'GEM_PATH=/tmp/build_c16174fa21307792629df435f91cd5ae/vendor/bundle/ruby/2.6.0', execute `gem env` for more information
 !     
 !     To install the version of bundler this project requires, run `gem install bundler -v '2.0.2'`
 !
/app/tmp/buildpacks/19b20846a186a4065aa6710b809d0c465ff7a2235264402d06b5038f9562c56867a32c308dd2410d96108925a9f9fed74b5ef871dd6514a3a3a5485da3f442cf/lib/language_pack/helpers/rake_runner.rb:106:in `load_rake_tasks!': Could not detect rake tasks (LanguagePack::Helpers::RakeRunner::CannotLoadRakefileError)
ensure you can run `$ bundle exec rake -P` against your app
and using the production group of your Gemfile.
Activating bundler (2.0.2) failed:
Could not find 'bundler' (2.0.2) required by your /tmp/build_c16174fa21307792629df435f91cd5ae/Gemfile.lock.
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:2.0.2`
Checked in 'GEM_PATH=/tmp/build_c16174fa21307792629df435f91cd5ae/vendor/bundle/ruby/2.6.0', execute `gem env` for more information
To install the version of bundler this project requires, run `gem install bundler -v '2.0.2'`
    from /app/tmp/buildpacks/19b20846a186a4065aa6710b809d0c465ff7a2235264402d06b5038f9562c56867a32c308dd2410d96108925a9f9fed74b5ef871dd6514a3a3a5485da3f442cf/lib/language_pack/ruby.rb:885:in `rake'

然而，这很奇怪，因为在我的Gemfile.lock中它说：

RUBY VERSION
   ruby 2.6.3p62

BUNDLED WITH
   2.0.2

当我执行ruby -v和bundler -v时，这一点得到了证实。 谁能明白为什么这个推送被拒绝了？

Answer 1

原来我必须更新 buildpack：

heroku buildpacks:set heroku/ruby

在此过程的后期仍然存在问题，但这似乎解决了该特定问题。