database configuration does not specify adapter - ruby-on-rails

Question

I'm getting this error when I'm trying to connect to a mysql database. The problem is that the application works for weeks, and then randomly I get this message. When I get this error message the application is not able to reconnect to the database until I restart it.
I'm using a configuration file to connect to the database, and the adapter is specified...the database configuration is not generated at runtime.
Do you have any idea on what is going on?

Answer 1

when I tried to run a command line script (let's say 'my_script' here), the same error happened. The reasons were:
There is only production environment there.
I missed to set RAILS_ENV for the command line.
So, the following is the solution in my case:
$ RAILS_ENV=production my_script

Answer 2

I just had this problem, and it was caused by a typo in my configration.yml.
I originally had this:
production:
adapter:mysql
When I meant to have this:
production:
adapter: mysql
That one little space between adapter: and mysql makes the difference.

Answer 3

Another possible cause:
In Rails 3.2.x, establish_connection has a default argument set from the environment:
From connection_specification.rb:
def self.establish_connection(spec = ENV["DATABASE_URL"])
resolver = ConnectionSpecification::Resolver.new spec, configurations
spec = resolver.spec
The way ConnectionSpecification::Resolver works depends on ENV['DATABASE_URL'] giving a nil if not set. (Normally, it would be something like 'postgres://...').
So, if you happen to have misconfigured DATABASE_URL such that ENV['DATABASE_URL'] == '', that will give you database configuration does not specify adapter.

Answer 4

I had this error when I mistakenly started rails server with
sudo rails s -e "Production" -p 80
and I should have started rails with
sudo rails s -e "production" -p 80

Answer 5

I found another thing that can cause this problem: "mixing in" another YAML node using & and *.
I was originally doing something like the following to facilitate local, per-develop, Git-ignored config files:
http://blog.lathi.net/articles/2006/03/02/config-database-yml-goodness-for-teams
But, after some debugging, I came to find out that establish_connection was for some reason being called with only the mixed-in key-value pairs and not the main ones. I.e. adapter, host, and database were not being passed in. I have no idea why, and this used to work for me.
Anyhow, instead of mixing in another YAML node, I now put the entire development and test hashes in the local config file, and establish_connection is once again being called correctly.

Answer 6

For me, this command resolved the issue.
rake db:migrate RAILS_ENV=production

Answer 7

I've found a couple of clues that this might be related to older library (ActiveRecord) or gem versions. For example, problems with fixtures even though rest of app seems okay (after an upgrade) or this trac ticket, which "stops gems from requiring an adapter from an old Active Record gem". Both of these are old, though, but it might be worth making sure your gems are up to date (if possible).
Are you using the native rails MySQL adapter by any chance? This is now deprecated under rails, but it's conceivable it's still limping along.
I've taken a very quick look at connection_specification.rb, too, which is where this error is coming from, and my best guess is that a reconnect is failing... but why (since it was obviously okay when you first started the app)? Are you doing something wild like calling ActiveRecord::Base.establish_connection in your application controller (or elsewhere)?
Or perhaps something like: script runner is called from cron in the dead of night when the connection has dropped. Unfortunately, the runner is invoked with an incorrect RAILS_ENV. Thus the wrong stanza is read from database.yml, and that stanza contains an invalid adapter:?

Answer 8

I got the same error, by typing in the following command:
db:migrate RAILS_ENV=product
Should've been:
db:migrate RAILS_ENV=production

Answer 9

If you get this error while deploying with Capistrano. Make sure you are setting the correct RAILS_ENV via
set :rails_env, 'production'
For example I was not explicitly setting the Rails environment in for the Capistrano staging deployment configuration. And thus Capistrano used 'staging' as the RAILS_ENV, resulting in the above error. Setting it to production like above in the staging.rb file solved the issue.

Answer 10

Do remember that RAILS_ENV=staging will look for a staging specification in your database.yml just as setting RAILS_ENV=production will look for a production specification in database.yml file.
Provide database configs, as shown below, for every rails environment you target using, for example
bundle exec cap staging deploy
production:
adapter: mysql2
encoding: utf8
database: rails
username: rails
password: pass
host: 127.0.0.1
port: 3306
pool: 5
timeout: 5000
staging:
adapter: mysql2
encoding: utf8
database: rails
username: rails
password: pass
host: 127.0.0.1
port: 3306
pool: 5
timeout: 5000

Answer 11

Remember to use the C-Based ruby gem for mysql. The ruby-based is unstable for production.
Try installing the gem
gem install mysql
Remember to copy libmySQL.dll into the ruby bin directory.

Answer 12

I had this error with another problem; I had specified 'development' twice, and 'test' not at all.

Answer 13

There are alot of bad tutorials out there on the internet that show yaml files like so:
development:
encoding: utf
database: dbname
...etc
YAML files are case sensitive and require TWO SPACES for the inner contents of each given db-type attribute. Like so:
development:
encoding: utf
database: dbname
...etc
UPDATE: I got this error again today. My VPS server had installed Rails 3.2.8 when my app was running Rails 3.2.6.
Definitely check your Gemfile and your database.yml file (of course). The problem here is clearly stated---Rails is not communicating with your database specifically due to an adapter (aka gem)

Answer 14

We had this issue with one of our older apps. Someone had created a boutique named environment, that even if RAIL_ENV was set to production, it was looking for a database configuration called legacy_<RAIL_ENV>, so I had to make a database environment called legacy_production for this app to work.
If you are maintain someone else's app, I would look for a copy of this app's database.yml that is working, perhaps it has some oddly named configuration. You can search your codebase for establish_connection to see if it is defining some strange variant.

Answer 15

I met this problem due to the 'multiple database support issue'. In my app/model folder, there is a file defined a redundant database connection:
class CacheCleanerActiveRecord < ActiveRecord::Base
establish_connection "cache_cleaner_#{Rails.env}"
self.abstract_class = true
end
but this database is not found in my database.yml ( because it's not used at all ).
so the solution is quit simple: remove this file and everything is fine !

Answer 16

You may have an error like:
RAILS_ENV= test
A space after the equals sign is not allowed, change it to:
RAILS_ENV=test

Answer 17

This happens to me, finally I found that RAILS_ENV is case sensitive, in my enviroment I set
RAILS_ENV=DEVELOPMENT , which is wrong, the value of RAILS_ENV must be lowercase.
$ RAILS_ENV=DEVELOPMENT rails server webrick
=> Booting WEBrick
=> Rails 4.2.5 application starting in DEVELOPMENT on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
config.eager_load is set to nil. Please update your config/environments/*.rb files accordingly:
* development - set it to false
* test - set it to false (unless you use a tool that preloads your test environment)
* production - set it to true
Exiting
/home/fangxing/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/connection_specification.rb:248:in `resolve_symbol_c
onnection': 'DEVELOPMENT' database is not configured. Available: ["default", "development", "test", "production"] (ActiveRecord::AdapterNotSpecified)
from /home/fangxing/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.5/lib/active_record/connection_adapters/connection_specification.rb:211:in `res
olve_connection'
$ RAILS_ENV=development rails server webrick
RubyDep: WARNING: Your Ruby is outdated/buggy. (To disable warnings, set RUBY_DEP_GEM_SILENCE_WARNINGS=1)
RubyDep: WARNING: Your Ruby is: 2.3.0 (buggy). Recommendation: install 2.3.1.
=> Booting WEBrick
=> Rails 4.2.5 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2016-07-20 16:41:09] INFO WEBrick 1.3.1
[2016-07-20 16:41:09] INFO ruby 2.3.0 (2015-12-25) [x86_64-linux]
[2016-07-20 16:41:09] INFO WEBrick::HTTPServer#start: pid=19881 port=3000

Answer 18

rails -e "production" is okay
only rails -e production returns error
database configuration does not specify adapter (ActiveRecord::AdapterNotSpecified)

Answer 19

call rake assets:precompile:all

Answer 20

This is probably not the most likely issue to cause this error, but here it is just in case.
My problem was that I was building the database settings in a Hash using symbols as keys and then serializing it with #to_yaml to database.yaml. ActiveRecord expects the environment names to be Strings, not Symbols, so it wasn't picking up the database settings when reading the generated file. I fixed it by using string keys in the hash.

Answer 21

For Rails4, commenting the line fetch(:default_env).merge!(rails_env: 'production') in production.rb and adding set :rails_env, :production fixed it.

Answer 22

You need to specify the environment when running the server or command as your database.yml file may have only production adapter while simply runnig rake db:migrate for example will take environment variable as development.

Answer 23

Just for the sake of completeness, I just got this error because I natively created a parametrised Rails runner script that takes an email address, and named the command line option -e -- which of course is the one the Rails runner uses for the environment. So it was trying to find an environment configuration that matched the email address!
Luckily, just before the ActiveRecord error mentioned in the title, it gave me an error message that helped me twig what the problem actually was:
You did not specify how you would like Rails to report deprecation notices for your test#example.com environment, please set config.active_support.deprecation to :log, :notify or :stderr at config/environments/test#example.com.rb

Answer 24

Check the spelling of adapter I had adaptor and got this error.

Answer 25

I had this error message when upgrading from Rails 4 to 5. I was calling
establish_connection "myconnection"
where "myconnection" is a valid key in my database.yml. However, passing this parameter as a string is apparently no longer supported. Using a symbol instead got rid of the problem.

Answer 26

I got this from copying and pasting sudo rails server webrick –e production -d from documentation into the CLI.
I'll shut the door on my way out 😔