Ruby on rails 如何修复'；mysql2'；加载rails控制台时出错？_Ruby On Rails

Ruby on rails 如何修复'；mysql2'；加载rails控制台时出错？

ruby-on-rails

Ruby on rails 如何修复'；mysql2'；加载rails控制台时出错？,ruby-on-rails,Ruby On Rails,我正在尝试启动rails控制台（与我之前的问题无关，因为这些都是不同的错误），但我一辈子都不知道如何解决这个问题，甚至不知道要我做什么。我正在运行：ruby 2.6.3p62（2019-04-16修订版67580）[x86_64-linux] 我键入rails控制台命令并获得以下信息： ubuntu:~/environment/sample\u应用程序（注册）$rails控制台 /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/bundler/

我正在尝试启动rails控制台（与我之前的问题无关，因为这些都是不同的错误），但我一辈子都不知道如何解决这个问题，甚至不知道要我做什么。我正在运行：ruby 2.6.3p62（2019-04-16修订版67580）[x86_64-linux]

我键入rails控制台命令并获得以下信息：

ubuntu:~/environment/sample\u应用程序（注册）$rails控制台

/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/bundler/rubygems_integration.rb:408:in `block (2 levels) in replace_gem': Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? mysql2 is not part of the bundle. Add it to your Gemfile. (LoadError)
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/mysql2_adapter.rb:6:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/connection_specification.rb:169:in `spec'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:1052:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_handling.rb:51:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/railtie.rb:201:in `block (2 levels) in <class:Railtie>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `class_eval'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `block in execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:61:in `with_execution_control'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:66:in `execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:52:in `block in run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `each'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:327:in `<module:ActiveRecord>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:27:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:370:in `active_record_configured?'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:287:in `disconnect_database'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:111:in `preload'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:157:in `serve'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'
ubuntu:~/environment/sample_app (sign-up) $ rails console
/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/bundler/rubygems_integration.rb:408:in `block (2 levels) in replace_gem': Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? mysql2 is not part of the bundle. Add it to your Gemfile. (LoadError)
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/mysql2_adapter.rb:6:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/connection_specification.rb:169:in `spec'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:1052:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_handling.rb:51:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/railtie.rb:201:in `block (2 levels) in <class:Railtie>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `class_eval'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `block in execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:61:in `with_execution_control'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:66:in `execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:52:in `block in run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `each'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:327:in `<module:ActiveRecord>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:27:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:370:in `active_record_configured?'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:287:in `disconnect_database'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:111:in `preload'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:157:in `serve'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'

我尝试了给出的建议，但现在当我尝试运行“rails控制台”时，我的错误看起来是这样的。捆绑安装工作正常

ubuntu:~/environment/sample_app (sign-up) $ rails console
/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/bundler/rubygems_integration.rb:408:in `block (2 levels) in replace_gem': Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? can't activate mysql2 (>= 0.4.4), already activated mysql2-0.3.21. Make sure all dependencies are added to Gemfile. (LoadError)
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/mysql2_adapter.rb:6:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/connection_specification.rb:169:in `spec'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:1052:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/connection_handling.rb:51:in `establish_connection'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/railtie.rb:201:in `block (2 levels) in <class:Railtie>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `class_eval'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:71:in `block in execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:61:in `with_execution_control'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:66:in `execute_hook'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:52:in `block in run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `each'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active_support/lazy_load_hooks.rb:51:in `run_load_hooks'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:327:in `<module:ActiveRecord>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active_record/base.rb:27:in `<main>'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:370:in `active_record_configured?'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:287:in `disconnect_database'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:111:in `preload'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:157:in `serve'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
        from /home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from /home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from -e:1:in `<main>'

ubuntu:~/environment/sample\u应用程序（注册）$rails控制台
/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/bundler/rubygems_integration.rb:408:replace_gem中的block（2个级别）：加载“mysql2”活动记录适配器时出错。错过了它所依赖的宝石？无法激活mysql2（>=0.4.4），已激活mysql2-0.3.21。确保所有依赖项都已添加到该文件中。（加载错误）
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/connection\u adapters/mysql2\u adapter.rb:6:in`'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:23:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:23:in`block in require\u with\u bootsnap\u lfi'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/loaded\u features\u index.rb:92:in'register'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in`require_with_bootsnap_lfi'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:31:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/connection\u adapters/connection\u specification.rb:169:in'spec'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/connection\u adapters/abstract/connection\u pool.rb:1052:in“建立连接”
from/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/connection\u handling.rb:51:在“建立连接”中
from/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/railtie.rb:201:in“block（2层）in”
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u support/lazy\u load\u hooks.rb:71:in'class\u eval'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u-support/lazy\u-load\u-hooks.rb:71:in`block in execute\u-hook'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u support/lazy\u load\u hooks.rb:61:in`with_execution\u control'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u-support/lazy\u-load\u-hooks.rb:66:in'execute\u-hook'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u-support/lazy\u-load\u-hooks.rb:52:“运行中的块\u-load\u-hooks”
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u support/lazy\u load\u hooks.rb:51:in'each'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activesupport-6.0.3.1/lib/active\u-support/lazy\u-load\u-hooks.rb:51:in'run\u-load\u-hooks'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/base.rb:327:in`'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/activerecord-6.0.3.1/lib/active\u record/base.rb:27:in`'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:23:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:23:in`block in require\u with\u bootsnap\u lfi'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/loaded\u features\u index.rb:92:in'register'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in`require_with_bootsnap_lfi'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/bootsnap-1.4.6/lib/bootsnap/load\u path\u cache/core\u ext/kernel\u require.rb:31:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in'require'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:370:在“活动记录配置”中
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:287:in'disconnect_database'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:111:in'preload'
from/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:157:in'serve'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:145:“运行中的块”中
from/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in'loop'
from/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application.rb:139:in'run'
来自/home/ubuntu/.rvm/gems/ruby-2.6.3/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in`'
来自/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core\u ext/kernel\u require.rb:54:in'require'
来自/home/ubuntu/.rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0/rubygems/core\u ext/kernel\u require.rb:54:in'require'
from-e:1:in`'

确保gem文件中包含“mysql2”，然后运行

捆绑安装

错误消息的关键部分是：

Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? mysql2 is not part of the bundle. Add it to your Gemfile.

如果您在安装gem时遇到问题，它可能会缺少一些操作系统级别d

Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? mysql2 is not part of the bundle. Add it to your Gemfile.