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ruby on rails - Installing MySQL2 Gem on Windows

I was having some issues getting the mysql2 gem to install on my Windows 8.1 machine. I followed the instructions in this post:

Ruby MYSQL2 gem installation on windows 7

to install the mysql2 gem, and I did not get any error messages.

I followed this with the

bundle install 

command, and confirmed that the following gems are installed (using bundle show), confirming that I have the following gems installed:

Using devise (3.2.2)
Using mysql2 (0.3.14)

Then I tried doing:

rails generate devise:install

and this is what I got:

C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/mysql2-0.3.14/lib/mysql2.rb:8:in `require': 126: The specified module could not be found.   
- C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/mysql2-0.3.14/lib/mysql2/ (LoadError)
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/mysql2-0.3.14/lib/mysql2.rb:8:in `<top (required)>'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:76:in `require'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:72:in `each'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:72:in `block in require'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:61:in `each'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler/runtime.rb:61:in `require'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/bundler-1.5.1/lib/bundler.rb:131:in `require'
    from C:/Users/Joseph/googledrive/projects/rails/test_new_devise/config/application.rb:7:in `<top (required)>'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.0.2/lib/rails/commands.rb:43:in `require'
    from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.0.2/lib/rails/commands.rb:43:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

Any ideas?


The answer is a combination of two answers from stackoverflow, plus modifications. The stackoverflow references are:

Ruby MYSQL2 gem installation on windows 7 ...mysql2/ [BUG] Segmentation fault ruby 2.0.0p247

Bottom line: to get mysql2 working in a 64 bit environment with Ruby 2 on Windows 8.1, you need to do the following:

  1. Clean up: the reason you're here is that you're probably been trying to install this gem, and it has failed, so you have some cleanup to do: gem uninstall mysql2

  2. Download Ruby 2.0 64 bit for Windows:

  1. Run the installer. Note the directory it installs to, and make sure it's in the User PATH. go to

    Control Panel > System and Security > System - Advanced System Settings > Environment Variables

and make sure the path to the bin directory of the ruby install directory is in the PATH environment variable for the LOCAL user (it's also OK if it's in the SYSTEM Path environment variable)

  1. Download the Ruby 2 64 bit Dev Kit:

  1. Run the installer and note the location of the install directory. The instructions say that once you're done with the install, you need to run the devkitvars.bat file to set the environment variables. This DOES NOT work for Windows 8.1. You need to repeat the instructions to set the local path described in #2 above, to set the path environment variable for the local user to add the ruby dev kit bin directory, and the ruby dev kit mingw bin directory. For example, if the dev kit was installed to c:\ruby2devkit, and you installed ruby2 to the C:\Ruby200-x64 directory, then your edit your path statement to look like this:

  2. Next you need to install the mysql-connector. DO NOT download and run the self-installer. Instead, download the zip file and unpack it. Note the directory you unpacked it to (for the purposes of this post, let's assume you unpacked it to c:\mysql-connector:

    Recommend:ruby on rails - installing mysql2 gem errors

    ode I installed ruby and ruby gems through macport but the gem list does not include mysql2. So how would i get mysql2 gem installed inside my gem list which is inside "/opt/local/bin/gem" Also, what is the mysql2 gem I have mysql gem and

  1. The libmysql.lib included in the MySQL Connector 64 bit is not compatible with the mingw64-gcc compiler. You need to generate mingw64 compatible libmysql.lib file.

  2. Download the tools you need

  3. Unzip this file to a local directory, let's assume that you unzipped it to c:\svm-map

  4. Edit the PATH environment path, as described earlier, to now look like this:

  5. Generate the new mysql libraries:

    (make sure you're running as administrator)
    cd c:\mysql-connector\lib
    gendef.exe libmysql.dll
    dlltool -v --dllname libmysql.dll --def libmysql.def --output-lib libmysql.lib
    copy libmysql.dll C:\Ruby200-x64\bin
    copy libmysql.lib C:\Ruby200-x64\bin
  6. Install the gem as follows (note the use of forward slashes instead of backslashes, it will fail if you use backslashes):

    gem install mysql2 --platform=ruby -- '--with-mysql-dir="C:/mysql-connector/"'

Hope this helps, and hopefully someone will pay attention to the few Windows 8.1 users who want to do Ruby on Rails development.

ruby-on-rails ruby-on-rails-4 mysql2
  this question
edited Nov 6 '14 at 6:40 asked Jan 14 '14 at 23:35 EastsideDeveloper 1,260 21 48      try gem install mysql2 –  house9 Jan 14 '14 at 23:41 1   the mysql2 gem is already installed. Please read my question. –  EastsideDeveloper Jan 14 '14 at 23:51      I run windows8.1 64-bit with 64-bit Ruby 2.0. I can confirm that this solution works. I had to take one additional set prior to #9. I had to delete the mysql2 gem's already installed by Bundle. Bundle failed to install them mysql gem when I attempted other peoples solutions, but it still created the gem directory and installed some files. Deleting them prior to step 9 made it work! –  Peter Kirby May 12 '14 at 18:01      Thanks Peter Kirby. I will add this as step 0. –  EastsideDeveloper May 13 '14 at 5:17      At step 10, I recommend perform the commands using administrator privileges. gendef.exe doesn't inform that the file libmysql.def was not generated. –  Cigano Morrison Mendez Oct 4 '14 at 19:50


1 Answers

When you installed the mysql2, did you download the lib files it needs?

I've not installed it on Windows 8, but Windows 7 needs to have this file to give mysql the dependencies requires to help it work. You can see various tutorials on how to do this, and I'll outline a simple overview here:

- Unzip the mysql connector file:

C:\mysql-connector-c-6.1.3-win32\ (or similar path WITHOUT any spaces)

- Run the mysql2 gem installer again:

gem uninstall mydsql
gem install mysql2 --platform=ruby -- '--with-mysql-lib="C:\mysql-connector\lib" --with-mysql-include="C:\mysql-connector\include" --with-mysql-dir="C:\mysql-connector"'

Bottom line is I think your mysql2 gem isn't loading the files it requires to run, and probably doesn't show an error because it's Windows 8

  this answer
answered Jan 15 '14 at 9:38 Richard Peck 59.5k 7 43 87 1   I am using the 64 bit connector, not the 32 bit. Other than that, if you look at my original question, I said that I followed the instructions in the link I included, and that's a more expanded version of the suggestion you provide here. Only issue is that the example you provided does not work, because it's using Windows style directory separator, but the installer expects Linux style directory separators. –  EastsideDeveloper Jan 15 '14 at 18:18      See the edits to my answers –  EastsideDeveloper Jan 18 '14 at 20:40      Nice! You fixed it!! –  Richard Peck Jan 18 '14 at 20:46 1   With windows 8 & connector 6.1.6 you must ONLY set mysql-dir: gem install mysql2 --platform=ruby -- '--with-mysql-dir="C:\mysql-connector-c-6.1.6-winx64"' –  ndesorden Jan 18 '16 at 10:14      Thanks bud - which version of Ruby are you running? –  Richard Peck Jan 18 '16 at 10:18


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more details. I followed instructions from the following location: I am using ruby 1.9.2p136 (2010-12-25) [i386-mingw32]. Here is what I get: E:\work_desk\trunk>gem install mys


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