我在启动我在bluehost上托管的rails应用程序时遇到了一些问题。
我认为问题是乘客版本与rails 4应用程序交互，但我不确定。
当我启动我的应用程序时，我得到了这个痕迹：
Ruby (Rack) application could not be started
These are the possible causes:
There may be a syntax error in the application's code. Please check for such errors and fix them.
A required library may not installed. Please install all libraries that this application requires.
The application may not be properly configured. Please check whether all configuration files are written correctly, fix any incorrect configurations, and restart this application.
A service that the application relies on (such as the database server or the Ferret search engine server) may not have been started. Please start that service.
Further information about the error may have been written to the application's log file. Please check it in order to analyse the problem.
Error message:
Could not initialize MySQL client library
Exception class:
RuntimeError
Application root:
/home5/barracam/rails_apps/admin/admin
Backtrace:
# File Line Location
0 /home5/barracam/ruby/gems/gems/mysql2-0.3.18/lib/mysql2.rb 31 in `require'
1 /home5/barracam/ruby/gems/gems/mysql2-0.3.18/lib/mysql2.rb 31 in `'
2 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 72 in `require'
3 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 72 in `block (2 levels) in require'
4 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 70 in `each'
5 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 70 in `block in require'
6 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 59 in `each'
7 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler/runtime.rb 59 in `require'
8 /usr/lib64/ruby/gems/1.9.3/gems/bundler-1.3.5/lib/bundler.rb 132 in `require'
9 /home5/barracam/rails_apps/admin/admin/config/application.rb 7 in `'
10 /home5/barracam/rails_apps/admin/admin/config/environment.rb 2 in `require'
11 /home5/barracam/rails_apps/admin/admin/config/environment.rb 2 in `'
12 config.ru 3 in `require'
13 config.ru 3 in `block in'
14 /home5/barracam/ruby/gems/gems/rack-1.5.2/lib/rack/builder.rb 55 in `instance_eval'
15 /home5/barracam/ruby/gems/gems/rack-1.5.2/lib/rack/builder.rb 55 in `initialize'
16 config.ru 1 in `new'
17 config.ru 1 in `'
18 /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb 225 in `eval'
19 /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb 225 in `load_rack_app'
20 /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb 157 in `block in initialize_server'
21 /etc/httpd/modules/passenger/lib/phusion_passenger/utils.rb 563 in `report_app_init_status'
22 /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb 154 in `initialize_server'
23 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb 204 in `start_synchronously'
24 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb 180 in `start'
25 /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb 129 in `start'
26 /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb 253 in `block (2 levels) in spawn_rack_application'
27 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb 132 in `lookup_or_add'
28 /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb 246 in `block in spawn_rack_application'
29 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb 82 in `block in synchronize'
30 prelude> 10:in `synchronize'
31 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb 79 in `synchronize'
32 /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb 244 in `spawn_rack_application'
33 /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb 137 in `spawn_application'
34 /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb 275 in `handle_spawn_application'
35 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb 357 in `server_main_loop'
36 /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb 206 in `start_synchronously'
37 /etc/httpd/modules/passenger/helper-scripts/passenger-spawn-server 99 in `'
Powered by Phusion Passenger, mod_rails / mod_rack for Apache and Nginx.
我尝试运行rails 3应用程序，一切正常。你怎么看待这个问题？
非常感谢任何帮助。
答案 0 :(得分：1)
我得到了同样的错误，所以经过大量的研究，试验和错误......我将我的mysql2 gem锁定在3.0.16版本，并设置了我的database.yml，如下所示：
adapter: mysql2
encoding: utf8
database: store
username: root
password:
host: localhost
reconnect: true
port: 3306
我的应用程序在4.20上运行rails，现在运行正常。 （虽然连接到mysql数据库时仍然存在零星的麻烦？也许最蓝的服务器会过载？没有真正的模式，并且它不会经常发生。
答案 1 :(得分：0)
尝试更改database.yml
使用mysql代替mysql2适配器