Ruby on Rails 6 Gem::LoadError on aws-sdk-s3 Gem

The error you’re encountering, Gem::LoadError stating that the gem “aws-sdk-s3” can’t be activated because another version of the gem has already been activated, is a common issue in Ruby on Rails applications. This usually occurs when there’s a version conflict between gems in your application.

To resolve this issue, you’ll need to ensure that there’s consistency in gem versions across your application, especially with the “aws-sdk-s3” gem. Here are steps to help you resolve this:

1. Check Gemfile and Gemfile.lock:

Verify that the gem “aws-sdk-s3” is specified in your Gemfile and that the version is compatible with other gems in your application. Check the Gemfile.lock for the specific version that’s causing the conflict.

2. Specify Gem Versions:

Ensure you have specified the correct version for the “aws-sdk-s3” gem in your Gemfile. If not, add the correct version, or use a version constraint (e.g., “~> 3.0”) to allow flexibility while ensuring compatibility.

gem 'aws-sdk-s3', '~> 3.0'

3. Update Gems:

Run bundle update to update all gems in your application to their specified versions or within the specified version constraints.

4. Check Gemfile.lock:

After running bundle update, check the Gemfile.lock again to ensure that the “aws-sdk-s3” gem version is updated and consistent.

5. Deploy to Heroku:

Push the updated code to Heroku to deploy the application with the corrected gem versions.

git add .

git commit -m "Fix gem version conflict"

git push heroku master

6. Verify the Deployment:

After the deployment is successful, verify the application on Heroku to ensure that the gem version conflict is resolved.