RuntimeError with mysql2 and rails3 (bundler)

Question

I get this error

`establish_connection': Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (no such file to load -- active_record/connection_adapters/mysql2_adapter) (RuntimeError) from /opt/ruby-enterprise-1.8.7-2010.02/lib/ruby/gems/1.8/gems/activerecord- 

Here the dump of the whole error and my config and gemfile.

Answer 1

I had the same error after upgrading from Ubuntu from 11.10 to 12.04. Here is how I fixed the problem:

 gem uninstall mysql2 bundle 

I think the key here is the "native extensions" - I believe that when I installed the latter, I used a different version of mysql.

 Installing mysql2 (0.3.11) with native extensions 

Answer 2

I was getting the same error when using rails 3.0.7 and mysql2 0.3.2. The solution I found here is to use an older version of mysql2. So edit your gemfile in

 gem 'mysql2', '< 0.3' 

and run

 bundle install 

Answer 3

You also need to change the adapter from mysql to mysql2 in database.yml, as said here Install the mysql2 gem on Snow Leopard for Rails 3 with rvm

From:

development: adapter: mysql

To:

development: adapter: mysql2

Answer 4

Did you include the mysql2 gem file in your gemfile instead of the old mysql gem and subsequently installed the package?

Answer 5

If you are using rvm and may have added mysql2 outside of rvm, do the following: Confirm that your Gemfile says:

 gem 'mysql2' 

or for Rails2.x:

 gem 'mysql2', '~> 0.2.11' 

then

 $ cd RAILS_ROOT $ gem uninstall mysql2 Select gem to uninstall: 1. mysql2-0.2.11 2. mysql2-0.3.6 3. All versions > 3 # select "All versions" $ rvm gemset install mysql2 $ bundle install 

Now the rails should start properly.

Answer 6

This also fixed the issue I ran into:

 Please install the mysql2 adapter: `gem install activerecord-mysql2-adapter` (no such file to load -- active_record/connection_adapters/mysql2_adapter) 

You really need to run: gem install mysql2 and add the gem to your configuration.

Answer 7

just run "gem install mysql" also add the same to gemfile and run the package. worked

Answer 8

If someone is still having the problem of setting the mysql2 buffer with rails 3 on Windows, refer to the detailed installation instructions -

http://rorguide.blogspot.com/2011/03/installing-mysql2-gem-on-ruby-192-and.html

Answer 9

I am new to ruby, rails and Linux. Therefore, if this solution does not work, I am not responsible :)

Step 1:

 sudo gem uninstall mysql2 

Step 2:

 sudo gem install mysql -v 0.2.7 

Run webrick, if the same problem still appears, reinstall the rails.

This solution works for me.

Answer 10

Same problem for me too. Updated to Rails 3.1.rc4, and then downgraded to 3.0.3. Worked for me.

Answer 11

from 0.3.0 and ActiveRecord 3.1 - the ActiveRecord adapter was pulled out of this gem by itself in ActiveRecord. If you need to use mysql2 with Rails versions <3.1 make sure and specify the gemstone "mysql2", "~> 0.2.7" in your Gemfile

the missing file ( no such file to load ) can be found in mysql2 versions up to version 0.3.0.

given in mysql2 documentation