当我尝试使用“$ rails s”运行我的localhost时，我一直收到此错误：
（Mac OSX 10.8.3） （ruby 2.0.0p195（2013-05-14修订版40734）[x86_64-darwin12.3.0]） （Rails 3.2.11） （psql（PostgreSQL）9.2.2）**用自制软件安装
我一直在做很多卸载postgresql并重新安装所以我预感到某些地方可能存在冲突的库...我只是不知道从哪里开始。
我在同一个文件夹中安装了Postgresql 9.1和9.2，只是将9.1移到了垃圾箱中。
这是我在终端
中运行“rails s”时的输出Danny$ rails s
^[b=> Booting Thin
=> Rails 3.2.11 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:1208:in `initialize': could not connect to server: Connection refused (PGError)
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 5433?
could not connect to server: Connection refused
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 5433?
could not connect to server: Connection refused
Is the server running on host "localhost" (fe80::1) and accepting
TCP/IP connections on port 5433?
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:1208:in `new'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:1208:in `connect'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:326:in `initialize'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `new'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/postgresql_adapter.rb:28:in `postgresql_connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
from /Users/Danny/.rvm/rubies/ruby-2.0.0-p195/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
from /Users/Danny/.rvm/rubies/ruby-2.0.0-p195/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/model_schema.rb:308:in `clear_cache!'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activerecord-3.2.11/lib/active_record/railtie.rb:97:in `block (2 levels) in <class:Railtie>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/callbacks.rb:418:in `_run__3642716200177086041__prepare__4186317719333288752__callbacks'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/callbacks.rb:405:in `__run_callback'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/callbacks.rb:385:in `_run_prepare_callbacks'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/callbacks.rb:81:in `run_callbacks'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/actionpack-3.2.11/lib/action_dispatch/middleware/reloader.rb:74:in `prepare!'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/actionpack-3.2.11/lib/action_dispatch/middleware/reloader.rb:48:in `prepare!'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/application/finisher.rb:47:in `block in <module:Finisher>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/initializable.rb:30:in `run'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/initializable.rb:55:in `block in run_initializers'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `each'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/application.rb:136:in `initialize!'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/Danny/Dropbox/programming/coding/f_app/config/environment.rb:7:in `<top (required)>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `block in require'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:236:in `load_dependency'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/activesupport-3.2.11/lib/active_support/dependencies.rb:251:in `require'
from /Users/Danny/Dropbox/programming/coding/f_app/config.ru:3:in `block in <main>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/builder.rb:51:in `instance_eval'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/builder.rb:51:in `initialize'
from /Users/Danny/Dropbox/programming/coding/f_app/config.ru:in `new'
from /Users/Danny/Dropbox/programming/coding/f_app/config.ru:in `<main>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/builder.rb:40:in `eval'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/builder.rb:40:in `parse_file'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/server.rb:200:in `app'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/commands/server.rb:46:in `app'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/server.rb:304:in `wrapped_app'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/rack-1.4.5/lib/rack/server.rb:254:in `start'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/commands/server.rb:70:in `start'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/commands.rb:55:in `block in <top (required)>'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/commands.rb:50:in `tap'
from /Users/Danny/.rvm/gems/ruby-2.0.0-p195/gems/railties-3.2.11/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
答案 0 :(得分：18)
错误消息是有用的：
could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5433?
您可能尝试连接错误的端口 标准端口 5432 。检查你是如何（以及是否）启动postgres服务器的：
postgres@db:~$ ps -auxww | grep ^postgres
... <stripped more lines>
postgres 1274 0.0 0.3 1437240 57308 ? S May27 5:01 /usr/lib/postgresql/9.1/bin/postgres -D /var/lib/postgresql/9.1/main -c config_file=/etc/postgresql/9.1/main/postgresql.conf
The manual has related information here.
在我的示例中，使用了来自/etc/postgresql/9.1/main/postgresql.conf的设置，其中说明了（在许多其他设置中）：
port = 5432
或运行
netstat -nlp | grep postgres
或者只看这里（至少在Debian或Ubuntu中）：
ls -lA /var/run/postgresql/
如果您创建新的数据库群集，PostgreSQL会选择下一个空闲端口。由于您反复安装，您可能会混淆端口号。
listen_addresses 或者你只是forgot to allow TCP/IP connections。这些相关答案的更多信息：
- Run batch file with psql command without password
- What's the difference between "local" and "localhost" connection types in pg_hba.conf?
- no pg_hba.conf entry for host
答案 1 :(得分：2)
在我的情况下，问题是由于在Ubuntu 16.04中将postgresql-9.4升级到postgresql-9.5引起的。由于，在某个时间点安装了两个版本，后来安装的版本即postgresql-9.5的配置更改为默认端口5433（而不是标准默认5432）。
当我的Rails项目尝试连接到postgresql的默认端口时出现问题（因为端口未在database.yml文件中明确定义）并且一直失败。即使在删除了postgresql-9.4之后。
解决方案是更新postgresql（9.5）配置中的端口。为此，请打开文件/etc/postgresql/9.5/main/postgresql.conf并更改行
port = 5433 # (change requires restart)
到
port = 5432 # (change requires restart)
然后使用sudo service postgresql restart重新启动服务器。
或者，您可以更改导轨＆＃39; database.yml文件明确提到新端口（即5433）而不更改postgresql的配置文件。要做到这一点，只需添加一行这样的
port: 5433
并重新启动rails服务器。
答案 2 :(得分：2)
sudo -u postgres pg_ctlcluster 9.3 main stop
接着是
sudo -u postgres pg_ctlcluster 9.3 main restart
为我工作
答案 3 :(得分：1)
这可以解决问题：-
在SQL提示符下使用命令SHOW config_file;和SHOW hba_file;获取hba.conf文件地址
现在打开hba.conf并添加此host all all 0.0.0.0/0 trust
现在打开postgresql.conf并添加listen_address = '*'
答案 4 :(得分：0)
在postgresql.conf中，/ var / lib / pgsql / data / postgresql.conf：
1.更改listen_addresses =＆＃39; localhost＆＃39; to listen_addresses =＆＃39; *＆＃39;
2.启用默认端口为5432，port = 5432
同样在pg_hba.conf中，/ var / lib / pgsql / data /pg_hba.conf：
尝试将身份验证方法视为信任
答案 5 :(得分：0)
我收到此错误消息（从Jira端连接到Jira），解决方案是更改“数据库服务器的主机名或IP地址”。到“本地主机”。如果您在本地运行，则不能只输入本地IP地址。
此外，本地安装的下一个问题是密码始终会失败，即使这是正确的，因为pg_hba.conf需要进行编辑，因此身份验证方法是“信任”。