Software⏱️ 3 min read📅 2026-06-04

How to Fix: Error when trying to install app with mysql2 gem

Error installing mysql2 gem with ruby and rails application.

Quick Answer: The issue is likely due to the missing development library for MySQL. Try installing the 'libmysql-dev' package on Ubuntu/Debian or 'mysql-devel' on Red Hat/CentOS.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🚀 How to Resolve This Issue
  3. ✨ Wrapping Up

Error installing mysql2 gem with Ruby on Rails 3.2.21 can be frustrating, especially when trying to deploy or run an open-source application that relies on this gem. This issue affects developers who use the mysql2 gem in their Rails applications and are experiencing difficulties during the installation process.

This error is particularly frustrating because it prevents the developer from successfully running the bundle command, which is essential for setting up and deploying the application. However, by following the steps outlined below, you should be able to resolve this issue and get your application up and running smoothly.

⚠️ Common Causes

  • The primary reason for this error is that the mysql2 gem requires a C compiler to build its native extensions, but it's not installed on your system. This can happen when you're using a Ruby version manager like RVM or rbenv, which may not include a C compiler by default.
  • Another possible cause of this error is that the mysql2 gem is not compatible with your version of Ruby. If you're using an older version of Ruby, it's possible that the gem requires a newer version to build its native extensions.

🚀 How to Resolve This Issue

Installing the C compiler and updating Ruby

  1. Step 1: Step 1: Install the C compiler on your system. For Mac users using Homebrew, run the command 'brew install gcc' in your terminal. For Linux users, you can use the package manager to install the C compiler, or compile it from source.
  2. Step 2: Step 2: Update Ruby to the latest version. Run the command 'rvm update all' to update all installed Ruby versions. Then, run 'rvm install ruby-2.1.2' (or a newer version if available) to update your current Ruby version.
  3. Step 3: Step 3: Reinstall the mysql2 gem after updating Ruby and installing the C compiler. Run the command 'gem install mysql2' in your terminal.

Using an alternative database adapter

  1. Step 1: Step 1: Replace the mysql2 gem with a different database adapter that doesn't require building native extensions, such as the 'mysql' gem. Run the command 'gem install mysql' in your terminal.
  2. Step 2: Step 2: Update your Rails application's configuration to use the new database adapter. Open the 'config/database.yml' file and update the 'adapter' setting to 'mysql'.

✨ Wrapping Up

By following these steps, you should be able to resolve the error when trying to install the mysql2 gem with Ruby on Rails 3.2.21. Remember to always keep your system and application software up-to-date to avoid such issues in the future.

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