Ruby-on-rails PG::ConnectionBad - 无法连接到服务器：连接被拒绝

PG::ConnectionBad - could not connect to server: Connection refused

提问by fadelakin

Every time I run my rails 4.0 server, I get this output.

每次我运行 Rails 4.0 服务器时，我都会得到这个输出。

Started GET "/" for 127.0.0.1 at 2013-11-06 23:56:36 -0500

PG::ConnectionBad - could not connect to server: Connection refused
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (fe80::1) and accepting
TCP/IP connections on port 5432?
:
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:825:in `connect'
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:542:in `initialize'
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:41:in `postgresql_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:440:in `new_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:450:in `checkout_new_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:421:in `acquire_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:356:in `block in checkout'
 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `checkout'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'
 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'
 activerecord (4.0.0) lib/active_record/connection_handling.rb:79:in `retrieve_connection'
 activerecord (4.0.0) lib/active_record/connection_handling.rb:53:in `connection'
 activerecord (4.0.0) lib/active_record/migration.rb:792:in `current_version'
 activerecord (4.0.0) lib/active_record/migration.rb:800:in `needs_migration?'
 activerecord (4.0.0) lib/active_record/migration.rb:379:in `check_pending!'
 activerecord (4.0.0) lib/active_record/migration.rb:366:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
 activesupport (4.0.0) lib/active_support/callbacks.rb:373:in `_run__1613334440513032208__call__callbacks'
 activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks'
 actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:84:in `protected_app_call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:79:in `better_errors_call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:56:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
 railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app'
 railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged'
 railties (4.0.0) lib/rails/rack/logger.rb:21:in `call'
 quiet_assets (1.0.2) lib/quiet_assets.rb:18:in `call_with_quiet_assets'
 actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
 rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
 rack (1.5.2) lib/rack/runtime.rb:17:in `call'
 activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
 rack (1.5.2) lib/rack/lock.rb:17:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call'
 railties (4.0.0) lib/rails/engine.rb:511:in `call'
 railties (4.0.0) lib/rails/application.rb:97:in `call'
 rack (1.5.2) lib/rack/content_length.rb:14:in `call'
 thin (1.5.1) lib/thin/connection.rb:81:in `block in pre_process'
 thin (1.5.1) lib/thin/connection.rb:79:in `pre_process'
 thin (1.5.1) lib/thin/connection.rb:54:in `process'
 thin (1.5.1) lib/thin/connection.rb:39:in `receive_data'
 eventmachine (1.0.3) lib/eventmachine.rb:187:in `run'
 thin (1.5.1) lib/thin/backends/base.rb:63:in `start'
 thin (1.5.1) lib/thin/server.rb:159:in `start'
 rack (1.5.2) lib/rack/handler/thin.rb:16:in `run'
 rack (1.5.2) lib/rack/server.rb:264:in `start'
 railties (4.0.0) lib/rails/commands/server.rb:84:in `start'
 railties (4.0.0) lib/rails/commands.rb:78:in `block in <top (required)>'
 railties (4.0.0) lib/rails/commands.rb:73:in `<top (required)>'
 bin/rails:4:in `<main>'

I'm running Mavericks OS X 10.9 so I don't know if that's the problem. I've tried everything I could but nothing seems to work. I've uninstalled and install both postgres and the pg gem multiple times now.

我正在运行 Mavericks OS X 10.9，所以我不知道这是否是问题所在。我已经尽我所能，但似乎没有任何效果。我已经多次卸载并安装 postgres 和 pg gem。

This is my database.yml file

这是我的 database.yml 文件

development:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_development
  pool: 5
  username: 
  password: 
  template: template0
  host: localhost
  port: 5432

test: &test
  adapter: postgresql
  encoding: unicode
  database: metals-directory_test
  pool: 5
  username: 
  password: 
  template: template0
  host: localhost
  port: 5432

staging:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_production
  pool: 5
  username:
  password:
  template: template0
  host: localhost

production:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_production
  pool: 5
  username:
  password:
  template: template0
  host: localhost

cucumber:
  <<: *test

回答by Chris Slade

It could be as simple as a stale PID file. It could be failing silently because your computer didn't complete the shutdown process completely which means postgresdidn't delete the PID(process id) file.

它可以像陈旧的PID 文件一样简单。它可能会静默失败，因为您的计算机没有完全完成关机过程，这意味着postgres没有删除PID（进程 ID）文件。

The PID file is used by postgres to make sure only one instance of the server is running at a time. So when it goes to start again, it fails because there is already a PIDfile which tells postgresthat another instance of the server was started (even though it isn't running, it just didn't get to shutdown and delete the PID).

postgres 使用 PID 文件来确保一次只有一个服务器实例正在运行。因此，当它再次启动时，它会失败，因为已经有一个PID文件告诉postgres服务器的另一个实例已启动（即使它没有运行，它也没有关闭并删除 PID） .

1. To fix it remove/rename the PID file. Find the postgres data directory. On macOS using homebrew it is in /usr/local/var/postgres/, or /usr/local/var/log/other systems it might be /usr/var/postgres/.
2. To make sure this is the problem, look at the log file (server.log). On the last lines you will see:

1. 要修复它，请删除/重命名 PID 文件。找到 postgres 数据目录。在使用自制软件的 macOS 上/usr/local/var/postgres/，/usr/local/var/log/它在/usr/var/postgres/.
2. 要确定这是问题所在，请查看日志文件 ( server.log)。在最后几行，您将看到：

FATAL: lock file "postmaster.pid" already exists
HINT: Is another postmaster (PID 347) running in data directory "/usr/local/var/postgres"?

致命：锁定文件“postmaster.pid”已经存在
提示：是否有另一个 postmaster (PID 347) 在数据目录“/usr/local/var/postgres”中运行？

1. If so, rm postmaster.pid

2. Restart your server. On a mac using launchctl (with homebrew) the following commands will restart the server.

   launchctl unload homebrew.mxcl.postgresql.plist  
   launchctl load -w homebrew.mxcl.postgresql.plist
   

   OR on newer versions of Brew

   brew services restart postgresql
   

3. 如果是这样的话， rm postmaster.pid

4. 重新启动您的服务器。在使用 launchctl（带有自制软件）的 mac 上，以下命令将重新启动服务器。

   launchctl unload homebrew.mxcl.postgresql.plist  
   launchctl load -w homebrew.mxcl.postgresql.plist
   

   或在较新版本的Brew 上

   brew services restart postgresql
   

回答by Jai Kumar Rajput

After a lot of searching and analysis, I found a solution if you are using ubuntu just write this command in your terminal and hit enter

经过大量的搜索和分析，我找到了一个解决方案，如果您使用的是 ubuntu，只需在终端中编写此命令并按 Enter

sudo service postgresql restart

This will restart your PostgreSQL, I hope this would be helpful for you.

这将重新启动您的 PostgreSQL，我希望这对您有所帮助。

回答by techdreams

This issue comes when postgres doesn't shut down properly. Here is how I resolved this issue in three simple steps.

当 postgres 未正确关闭时会出现此问题。以下是我如何通过三个简单的步骤解决此问题。

Step 1:Go to your postgres directory

第 1 步：转到您的 postgres 目录

Mac Userswill find this in /usr/local/var/postgres, others might look at /usr/var/postgres/.

Mac 用户会/usr/local/var/postgres在/usr/var/postgres/.

Step 2:Remove .pidfile by running this command.

步骤 2：.pid通过运行此命令删除文件。

rm postmaster.pid

Step 3:Restart your server

第 3 步：重新启动服务器

Mac Users

Mac 用户

brew services restart postgresql

Linux Users

Linux 用户

sudo service postgresql restart

Finally restart your app and you are good to go.

最后重新启动您的应用程序，一切顺利。

回答by Andrea Gherardi

I have managed to solve the problem by following the Chris Slade's answer, but to restart the server, I had to use the following commands:

我已经按照 Chris Slade 的回答设法解决了这个问题，但是要重新启动服务器，我必须使用以下命令：

launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist

that I found here(pjammer's answer down at the bottom)

我在这里找到的（pjammer 的答案在底部）

回答by Mihail Davydenkov

Do you have postgresql installed within your system? If not, then watch Install postgresql. After you successfully integrate postgresqlinto your system you can type something like that in your system terminal:

您的系统中是否安装了 postgresql？如果没有，请观看Install postgresql。成功将postgresql集成到您的系统后，您可以在系统终端中键入类似的内容：

which psql
#=> /usr/bin/psql

After that you need to create a user and database in postgresql like this:

之后，您需要在 postgresql 中创建一个用户和数据库，如下所示：

sudo su - postgres
psql

Then you can see the following within your terminal

然后您可以在终端中看到以下内容

postgres=#

Type there:

在那里输入：

CREATE USER yourname WITH PASSWORD 'passwordhere';
CREATE DATABASE metals-directory_production  WITH OWNER yourname;
GRANT ALL PRIVILEGES ON DATABASE metals-directory_production TO yourname;

After you do this, then you need to correct your database.yml. Probably you need something like that:

完成此操作后，您需要更正您的database.yml. 可能你需要这样的东西：

development:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_development
  pool: 5
  username: yourname
  password: passwordhere   ### password you have specified within psql
  host: localhost
  port: 5432               ### you can configure it in file postgresql.conf

Also if you have problems with postgresql it is good idea to check pg_hba.conf

此外，如果您在使用 postgresql 时遇到问题，最好检查pg_hba.conf

回答by K M Rakibul Islam

To fix these type of issues with Postgresand to work with Postgreson Mac OSX, this is probably the BESTand the EASIESTsolution that I have found so far:

要解决这些类型的问题与Postgres的，并与工作的Postgres上Mac OSX，这可能是最好的和最简单的解决方案，我迄今发现：

http://postgresapp.com/

http://postgresapp.com/

Just download, install and be happy :)

只需下载，安装并快乐:)

回答by IAmNaN

1. Uninstall pg:

   gem uninstall pg

2. Uninstall postgres:

   brew uninstall postgres

3. Nuke the postgres folder which might be lingering with a bunch of stale stuff it in:

   rm -rf /usr/local/var/postgres

4. Reboot (maybe unnecessary)

5. Reinstall pg:

   brew install postgres

6. My comment in Chris Slade's answer starts pg the hard way, now I use brew services which has simplified my life in so many ways:

   brew install services

7. And start pg with it:

   brew services start postgresql

8. Reinstall the gem:

   gem install pg

1. 卸载 pg：

   gem uninstall pg

2. 卸载 postgres：

   brew uninstall postgres

3. 核对 postgres 文件夹，该文件夹中可能存在一堆陈旧的东西：

   rm -rf /usr/local/var/postgres

4. 重新启动（可能没有必要）

5. 重新安装 pg：

   brew install postgres

6. 我在 Chris Slade 的回答中的评论以艰难的方式开始，现在我使用 brew 服务，它在很多方面简化了我的生活：

   brew install services

7. 并用它启动 pg：

   brew services start postgresql

8. 重新安装宝石：

   gem install pg

And bobsyouruncle.

和bobsyouruncle。

回答by Alexis

check the file postgresql.conf(on ubuntuis in /etc/postgresql/X.X/main/postgresql.conf) and look for the line that says:

检查文件postgresql.conf（ubuntu在/etc/postgresql/XX/main/postgresql.conf 中）并查找以下行：

listen_addresses="localhost"

try change it to:

尝试将其更改为：

listen_addresses="*"

it would be accepting every IP's, next check the line that says:

它将接受每个 IP，接下来检查以下行：

port=5432

and check if is the same port of your database.yml, by default on my postgresql-9.2 use 5433instead 5432, don't forget to restartthe postgres server,

并检查是否与您的 database.yml 端口相同，默认情况下在我的 postgresql-9.2 上使用5433而不是5432，不要忘记重新启动postgres 服务器，

Good Luck!

祝你好运！

回答by Neil Atkinson

As described by @Magne, the error PG::ConnectionBad - could not connect to server: Connection refusedcan be presented following a major/minor versionupgrade (e.g. 9.5 -> 9.6or 9 -> 10) of PostgreSQL.

正如@Magne 所描述的，该错误PG::ConnectionBad - could not connect to server: Connection refused可能会在 PostgreSQL的主要/次要版本升级（例如9.5 -> 9.6或9 -> 10）之后出现。

I got this error after having run brew upgrade postgresqlafter the release of PostgreSQL version 9.6. The problem is that major/minor version upgrades require additional steps to migrate old date to the new version.

brew upgrade postgresql在 PostgreSQL 9.6 版发布后运行后出现此错误。问题是主要/次要版本升级需要额外的步骤才能将旧版本迁移到新版本。

How to check if this is your problem

如何检查这是否是您的问题

You can check if this is the problem by checking the the latest brew formula PostgreSQL version installed with homebrew...

您可以通过检查与自制软件一起安装的最新 brew 公式 PostgreSQL 版本来检查这是否是问题...

$ brew info postgresql

/usr/local/Cellar/postgresql/9.5.4_1 (3,147 files, 35M)
Poured from bottle on 2016-10-14 at 13:33:28
/usr/local/Cellar/postgresql/9.6.1 (3,242 files, 36.4M) *
Poured from bottle on 2017-02-06 at 12:41:00

...and then comparing it to the current PG_VERSION

...然后将其与当前的 PG_VERSION 进行比较

$ cat /usr/local/var/postgres/PG_VERSION
9.5

If the PG_VERSION is less than the latest brew formula and the difference is a major/minor version change, then this is probably your problem.

如果 PG_VERSION 小于最新的 brew 公式并且差异是主要/次要版本更改，那么这可能是您的问题。

How to fix (i.e. how to upgrade the data)

如何修复（即如何升级数据）

Instructions below are for an upgrade from 9.5 to 9.6. Change the version numbers as appropriate for your own upgrade

以下说明适用于从 9.5 升级到 9.6。根据您自己的升级情况更改版本号

Step 1.Make sure PostgreSQL is switched off:

步骤 1.确保 PostgreSQL 已关闭：

$ launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
# or, with Homebrew...
$ brew services stop postgresql

Step 2.Make a new pristine database:

步骤 2. 创建一个新的原始数据库：

$ initdb /usr/local/var/postgres9.6 -E utf8

Step 3.Check what the old and new binary versions are:

步骤 3.检查旧的和新的二进制版本是什么：

$ ls /usr/local/Cellar/postgresql/
9.5.3   9.5.4   9.6.1

Note that in this example I am upgrading from 9.5.4 binary to 9.6.1 binary

请注意，在此示例中，我将从 9.5.4 二进制升级到 9.6.1 二进制

Step 4.Migrate the current data to the new database using the pg_upgradeutility.

步骤 4.使用pg_upgrade实用程序将当前数据迁移到新数据库。

$ pg_upgrade \
  -d /usr/local/var/postgres \
  -D /usr/local/var/postgres9.6 \
  -b /usr/local/Cellar/postgresql/9.5.4/bin/ \
  -B /usr/local/Cellar/postgresql/9.6.1/bin/ \
  -v

• -dflag specifies the current data directory
• -Dflag specifies the new data directory to be created
• -bspecifies the old binary
• -Bspecifies the new binary we're upgrading to

• -dflag 指定当前数据目录
• -Dflag 指定要创建的新数据目录
• -b指定旧的二进制文件
• -B指定我们要升级到的新二进制文件

Step 5.Move the old data directory out of the way

步骤 5.将旧数据目录移开

$ mv /usr/local/var/postgres /usr/local/var/postgres9.5

Step 6.Move newly created data directory to where PostgreSQL expects it to be

步骤 6.将新创建的数据目录移动到 PostgreSQL 期望的位置

$ mv /usr/local/var/postgres9.6 /usr/local/var/postgres

Step 7.Start PostgreSQL again

步骤 7.再次启动 PostgreSQL

$ launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
# or, if you're running a current version of Homebrew
$ brew services start postgresql

Step 8.If you're using the pg gem for Rails, you should recompile by uninstalling and reinstalling the gem (skip this step if you're not using the pg gem)

步骤 8.如果您使用的是用于 Rails 的 pg gem，您应该通过卸载并重新安装 gem 重新编译（如果您不使用 pg gem，请跳过此步骤）

$ gem uninstall pg
$ gem install pg

Step 9.(optional)After you've reassured yourself that everything is working OK, you can run regain some disk space with the following command:

步骤 9.（可选）在您确信一切正常后，您可以使用以下命令重新获得一些磁盘空间：

brew cleanup postgresql

...and if you're feeling really brave you can delete the old PostgreSQL data directory with the following command

...如果你真的很勇敢，你可以使用以下命令删除旧的 PostgreSQL 数据目录

rm -rf /usr/local/var/postgres9.5/

(This answer is based on an excellent blog post https://keita.blog/2016/01/09/homebrew-and-postgresql-9-5/with some additions)

（此答案基于一篇出色的博客文章https://keita.blog/2016/01/09/homebrew-and-postgresql-9-5/并添加了一些内容）

回答by Rosana Ruiz

This is what really helped me.

这才是真正帮助我的。

$ cd /usr/local/var/postgres/
$ rm postmaster.pid

Reference: http://alumni.lewagon.org/questions/60

参考：http: //alumni.lewagon.org/questions/60