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         


        

Answer 1

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

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

quoted from the documentation of mysql2

Answer 2

just run "gem install mysql" also add the same in gemfile and run bundle. worked

Answer 3

I was getting the same error while using rails 3.0.7 and mysql2 0.3.2. The solution, which I found here, is to use an older version of mysql2. Thus edit your gemfile to

gem 'mysql2', '< 0.3'

and run

bundle install 

Answer 4

I'm a beginner at ruby, rails, and linux. So if this solution did not work, I hold no responsibility :)

Step 1:

sudo gem uninstall mysql2

Step 2:

sudo gem install mysql -v 0.2.7

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

This solution works for me.

Answer 5

Did you include the mysql2 gem in your gemfile instead of the old mysql gem, and ran bundle install afterwards?

Answer 6

If you're using rvm, and possibly added mysql2 outside of rvm, try these steps: 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 rails should start properly.