aws-eventstream 1.4.0 / aws-partitions ≥ 1.1110 require Ruby ≥ 2.7 and break legacy aws-sdk-* gems on old Rubies

[laupow]

Describe the bug

What happened

• On 2025-06-02 aws-eventstream v1.4.0 was published and raised the minimum supported Ruby to 2.7 (see Dropping Ruby 2.5 and 2.6 Runtime support #3249)
• aws-partitions v1.1110 (and newer) did the same
• Long-standing versions of aws-sdk-s3 and other V3 service gems specify aws-eventstream (~> 1.0) or aws-partitions (~> 1) with no upper bound.
• When Bundler runs on Ruby 2.3–2.6 it selects the newest 1.x release and fails:

ERROR:  Error installing aws-sdk-s3:
	The last version of aws-eventstream (~> 1, >= 1.3.0) to support your Ruby & RubyGems was 1.3.2. Try installing it with `gem install aws-eventstream -v 1.3.2` and then running the current command again
	aws-eventstream requires Ruby version >= 2.7. The current ruby version is 2.6.10.210.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

aws-sdk-s3 gem versions released prior to June 2, 2025 continue to install on Ruby 2.6

Current Behavior

aws-sdk-s3 gem versions released prior to June 2, 2025 do not install on Ruby 2.6 due to dependency resolution issues

Reproduction Steps

1. docker run -it ruby:2.6 bash
2. gem install aws-sdk-s3 -v 1.150.0 (released May 13, 2024)

Fetching base64-0.3.0.gem
Fetching aws-sdk-s3-1.150.0.gem
Fetching aws-partitions-1.1130.0.gem
Fetching aws-sigv4-1.12.1.gem
Fetching aws-eventstream-1.4.0.gem
Fetching jmespath-1.6.2.gem
Fetching aws-sdk-core-3.226.3.gem
Fetching aws-sdk-kms-1.106.0.gem
Successfully installed jmespath-1.6.2
Successfully installed base64-0.3.0
ERROR:  Error installing aws-sdk-s3:
	The last version of aws-eventstream (~> 1, >= 1.3.0) to support your Ruby & RubyGems was 1.3.2. Try installing it with `gem install aws-eventstream -v 1.3.2` and then running the current command again
	aws-eventstream requires Ruby version >= 2.7. The current ruby version is 2.6.10.210.

Possible Solution

public documentation of workarounds (manually install your gem's dependencies)

Additional Information/Context

I'm aware of the public deprecation details, and nudging people forward is absolutely the right direction.

Gem name ('aws-sdk', 'aws-sdk-resources' or service gems like 'aws-sdk-s3') and its version

aws-sdk-s3

Environment details (Version of Ruby, OS environment)

Ruby 2.6

[mullermp]

Thanks for opening an issue. You mention that bundler is not selecting the appropriate versions but your reproduction steps are not using bundler, they are using gem install. As the blog post states, you will need to pin your gem versions including s3 and its dependencies.

[laupow]

Is a two-step install really required here? I pinned aws-sdk-s3 to 1.186.0 but had to pre-install these versions first to avoid the error:

• aws-eventstream 1.32
• aws-partitions 1.1103.0
• aws-sigv4 1.11.0
• aws-sdk-core 3.224.0
• aws-sdk-kms 1.20.0

Only after that did gem install aws-sdk-s3 -v 1.186.0 succeed. I expected gem to resolve compatible versions automatically. Is this behavior expected?

[mullermp]

Correct. gem install unfortunately does not resolve dependencies by ruby version. It's recommended to use a Gemfile and bundle install.

[laupow]

I see, thanks. That is unfortunate!

[github-actions]

This issue is now closed. Comments on closed issues are hard for our team to see.
If you need more assistance, please open a new issue that references this one.

[mullermp]

I believe also gem install can take multiple arguments for gem names and versions, so you can do it in one step, but you have to be explicit about versions.