Gem::LoadError for mysql2 gem, but it's already in Gemfile

Question

Gem::LoadError
Specified \'mysql2\' for database adapter, but the gem is not loaded.
Add `gem \'mysql2\'` to your Gemfile

This error occurred while

Answer 1

Here is how I fixed this:

 bundle config
 bundle config --delete without
 bundle install --deployment --without development test postgres

Credits: How do you undo bundle install --without

Answer 2

I solved the problem, installing the libmysqlclient-dev. sudo aptitude install libmysqlclient-dev and later run bundle.

Answer 3

Change to

gem 'mysql2', '~> 0.3.18'

in your Gemfile.

This thread on the official mysql2 Github says to do this. You need to declare that version number if you're rails version 4.x.x.

https://github.com/brianmario/mysql2/issues/675

Then run bundle update mysql2.

Answer 4

It doesn't load mysql2 gem because new version of mysql2(0.4.1) gem unable to load the mysql2_adaptor. This is working for me.

gem 'mysql2', '~> 0.3.13'

and run

bundle install

Answer 5

I'm brand spanking new to Ruby on Rails and websites but hears what worked for me.

I had to change my gemfile, gem 'mysql2' to gem 'mysql2', '~> 0.3.13' then in rails i typed bundle install then i tried rails s and got errors so then i tried bundle update mysql2 then in rails typed rails s, and it worked

Answer 6

Being Beginner to the ruby i could not figure out the line gem 'mysql2', '~> 0.3.18'

it simply means go to your rails project folder and then there is line for mysql2 it will be like 0.4* so you can change it to gem 'mysql2', '~> 0.3.18'

and as we have new definition, we have to rebuild the dependency so to do that simple command as explained on the top bundle install