这教程作为入门很不友好，一次过参杂了太多第三方 Gem，guard、livereload，mail_form，haml 这几个 gem 都是很小众的，出问题都不知道是哪一个。

把 bundle show 的结果贴上来，确认 mail_form 安装了没。

如果已经安装，启动 server 缺提示找不到，有可能是 guard 或者 livereload 导致重启不完整，命令行 ps 一下看看有没有 ruby 进程没退出，啊是 Windows，不懂 Windows 对应的命令是啥。

非常感谢您的解答。

以下是 bundle show 的结果。 H:\Ruby Program\blog (master) λ bundle show Gems included by the bundle:

• actioncable (6.0.3.2)
• actionmailbox (6.0.3.2)
• actionmailer (6.0.3.2)
• actionpack (6.0.3.2)
• actiontext (6.0.3.2)
• actionview (6.0.3.2)
• activejob (6.0.3.2)
• activemodel (6.0.3.2)
• activerecord (6.0.3.2)
• activestorage (6.0.3.2)
• activesupport (6.0.3.2)
• addressable (2.7.0)
• bindex (0.8.1)
• bootsnap (1.4.6)
• builder (3.2.4)
• bundler (1.17.2)
• byebug (11.1.3)
• capybara (3.33.0)
• childprocess (3.0.0)
• concurrent-ruby (1.1.6)
• crass (1.0.6)
• erubi (1.9.0)
• ffi (1.13.1)
• globalid (0.4.2)
• i18n (1.8.3)
• jbuilder (2.10.0)
• loofah (2.6.0)
• mail (2.7.1)
• marcel (0.3.3)
• method_source (1.0.0)
• mimemagic (0.3.5)
• mini_mime (1.0.2)
• mini_portile2 (2.4.0)
• minitest (5.14.1)
• msgpack (1.3.3)
• nio4r (2.5.2)
• nokogiri (1.10.9)
• public_suffix (4.0.5)
• puma (4.3.5)
• rack (2.2.3)
• rack-proxy (0.6.5)
• rack-test (1.1.0)
• rails (6.0.3.2)
• rails-dom-testing (2.0.3)
• rails-html-sanitizer (1.3.0)
• railties (6.0.3.2)
• rake (13.0.1)
• regexp_parser (1.7.1)
• rubyzip (2.3.0)
• sass-rails (6.0.0)
• sassc (2.4.0)
• sassc-rails (2.1.2)
• selenium-webdriver (3.142.7)
• sprockets (4.0.2)
• sprockets-rails (3.2.1)
• sqlite3 (1.4.2)
• thor (1.0.1)
• thread_safe (0.3.6)
• tilt (2.0.10)
• turbolinks (5.2.1)
• turbolinks-source (5.2.0)
• tzinfo (1.2.7)
• tzinfo-data (1.2020.1)
• web-console (4.0.3)
• webdrivers (4.4.1)
• webpacker (4.2.2)
• websocket-driver (0.7.2)
• websocket-extensions (0.1.5)
• xpath (3.2.0)
• zeitwerk (2.3.1)

确实，mail_form 没有被安装。 重新运行 gem install 后仍然显示没有安装…这是什么情况？

bundle install 看看输出。

您好 这个是输出。抱歉不知道为什么粘贴格式不太对。已编辑

H:\Ruby Program\blog (master)

λ bundle install

Using rake 13.0.1

Using concurrent-ruby 1.1.6

Using i18n 1.8.3

Using minitest 5.14.1

Using thread_safe 0.3.6

Using tzinfo 1.2.7

Using zeitwerk 2.3.1

Using activesupport 6.0.3.2

Using builder 3.2.4

Using erubi 1.9.0

Using mini_portile2 2.4.0

Using nokogiri 1.10.9 (x64-mingw32)

Using rails-dom-testing 2.0.3

Using crass 1.0.6

Using loofah 2.6.0

Using rails-html-sanitizer 1.3.0

Using actionview 6.0.3.2

Using rack 2.2.3

Using rack-test 1.1.0

Using actionpack 6.0.3.2

Using nio4r 2.5.2

Using websocket-extensions 0.1.5

Using websocket-driver 0.7.2

Using actioncable 6.0.3.2

Using globalid 0.4.2

Using activejob 6.0.3.2

Using activemodel 6.0.3.2

Using activerecord 6.0.3.2

Using mimemagic 0.3.5

Using marcel 0.3.3

Using activestorage 6.0.3.2

Using mini_mime 1.0.2

Using mail 2.7.1

Using actionmailbox 6.0.3.2

Using actionmailer 6.0.3.2

Using actiontext 6.0.3.2

Using public_suffix 4.0.5

Using addressable 2.7.0

Using bindex 0.8.1

Using msgpack 1.3.3 (x64-mingw32)

Using bootsnap 1.4.6

Using bundler 1.17.2

Using byebug 11.1.3

Using regexp_parser 1.7.1

Using xpath 3.2.0

Using capybara 3.33.0

Using childprocess 3.0.0

Using ffi 1.13.1 (x64-mingw32)

Using jbuilder 2.10.0

Using method_source 1.0.0

Using puma 4.3.5

Using rack-proxy 0.6.5

Using thor 1.0.1

Using railties 6.0.3.2

Using sprockets 4.0.2

Using sprockets-rails 3.2.1

Using rails 6.0.3.2

Using rubyzip 2.3.0

Using sassc 2.4.0 (x64-mingw32)

Using tilt 2.0.10

Using sassc-rails 2.1.2

Using sass-rails 6.0.0

Using selenium-webdriver 3.142.7

Using sqlite3 1.4.2

Using turbolinks-source 5.2.0

Using turbolinks 5.2.1

Using tzinfo-data 1.2020.1

Using web-console 4.0.3

Using webdrivers 4.4.1

Using webpacker 4.2.2

抱歉粘贴分行有些混乱，已经编辑

贴一下 Gemfile，看看有没有 mail_form，另外执行命令的路径有没有弄错。

随即使用 gem install mail_form 安装。并运行 bundle install

楼主是不是跳过了教程的第一步：Edit Gemfile

Gemfile：

source 'https://rubygems.org'

git_source(:github) { |repo| "https://github.com/#repo}.git{" }

ruby '2.6.6'

Bundle edge Rails instead: gem 'rails', github: 'rails/rails'

gem 'rails', '~> 6.0.3', '>= 6.0.3.2'

Use sqlite3 as the database for Active Record

gem 'sqlite3', '~> 1.4'

Use Puma as the app server

gem 'puma', '~> 4.1'

Use SCSS for stylesheets

gem 'sass-rails', '>= 6'

Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker

gem 'webpacker', '~> 4.0'

Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks

gem 'turbolinks', '~> 5'

Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder

gem 'jbuilder', '~> 2.7'

Use Redis adapter to run Action Cable in production

gem 'redis', '~> 4.0'

Use Active Model has_secure_password

gem 'bcrypt', '~> 3.1.7'

Use Active Storage variant

gem 'image_processing', '~> 1.2'

Reduces boot times through caching; required in config/boot.rb

gem 'bootsnap', '>= 1.4.2', require: false

group :development, :test do # Call 'byebug' anywhere in the code to stop execution and get a debugger console gem 'byebug', platforms: [:mri, :mingw, :x64_mingw] end

group :development do # Access an interactive console on exception pages or by calling 'console' anywhere in the code. gem 'web-console', '>= 3.3.0' end

group :test do # Adds support for Capybara system testing and selenium driver gem 'capybara', '>= 2.15' gem 'selenium-webdriver' # Easy installation and use of web drivers to run system tests with browsers gem 'webdrivers' end

Windows does not include zoneinfo files, so bundle the tzinfo-data gem

gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

！天哪您这么一说好像确实没有 edit gemfile……是我侠了。立刻改一下试试

加油 冲起来

冲！

冲鸭！