Solving the 'Push Rejected, Failed to Compile Ruby App' Error: A Comprehensive Guide

Encountering errors while deploying your Ruby app can be frustrating, especially when it's the infamous 'Push Rejected, Failed to Compile Ruby App' error. In this guide, we'll help you understand and resolve this issue by providing a step-by-step process to fix it. We'll also cover some frequently asked questions to make your Ruby app deployment smoother.

Table of Contents

  1. Understanding the Error
  2. Step-by-Step Solution
  1. FAQs

Understanding the Error

The 'Push Rejected, Failed to Compile Ruby App' error occurs when you try to deploy your Ruby app, and the platform (e.g., Heroku) fails to compile it. This issue can arise due to various reasons, such as an outdated Ruby version, missing dependencies, or incorrect configuration files.

Step-by-Step Solution

To fix the 'Push Rejected, Failed to Compile Ruby App' error, follow these steps:

Step 1: Check Your Gemfile

Ensure that your Gemfile has all the required dependencies and that there are no conflicts between them. To do this, check the following:

  • All necessary gems are present in the Gemfile.
  • There are no duplicate or conflicting gem versions. If there are multiple versions of a gem, specify the required version explicitly.
  • The Gemfile.lock file exists and is up-to-date.

For more information on managing your Gemfile, refer to the official Bundler documentation.

Step 2: Update Your Ruby Version

Ensure that you're using a compatible Ruby version for your app. Check the platform's documentation (e.g., Heroku's Ruby Support) to see the supported Ruby versions. Update your Ruby version if needed by following these steps:

  1. Update your .ruby-version file with the desired Ruby version.
  2. Update your Gemfile to include the same Ruby version:
ruby '2.7.3'

Step 3: Bundle Install and Commit

After updating your Ruby version and checking your Gemfile, run bundle install to update your Gemfile.lock. Then, commit the changes to your version control system (e.g., Git):

$ git add .ruby-version Gemfile Gemfile.lock
$ git commit -m "Update Ruby version and dependencies"

Step 4: Check Your Procfile

Verify that your Procfile has the correct configuration for your app. The Procfile should define the process types and commands needed to run your app. For example, a simple Ruby web app might have the following Procfile:

web: bundle exec puma -C config/puma.rb

For more information on configuring your Procfile, refer to the platform's documentation (e.g., Heroku's Procfile).

Step 5: Redeploy Your App

After completing the previous steps, redeploy your app to the platform (e.g., Heroku). If everything is configured correctly, the 'Push Rejected, Failed to Compile Ruby App' error should be resolved.


Q: How do I know which Ruby version my app requires?

Check your app's documentation or source code to determine the required Ruby version. You can also look for the .ruby-version file or the Gemfile, which may specify the Ruby version.

Q: Can I use a different Ruby version than the one specified in the Gemfile?

It's not recommended to use a different Ruby version than the one specified in the Gemfile. Doing so may cause compatibility issues and unexpected behavior in your app.

Q: What is the purpose of the Gemfile.lock?

The Gemfile.lock file ensures that your app uses the same gem versions across different environments and installations. It's generated by Bundler when you run bundle install and should be committed to your version control system.

Q: How do I install a specific version of a gem?

To install a specific version of a gem, add the version number to the gem declaration in your Gemfile. For example:

gem 'rails', '6.1.4'

Then, run bundle install to update your Gemfile.lock.

Q: Can I deploy my Ruby app without a Procfile?

Yes, you can deploy your Ruby app without a Procfile. However, the platform may use default settings that might not be optimal for your app. It's recommended to include a Procfile with the appropriate configuration for your app.

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