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Ruby 3.3 managed runtime pre-activates bigdecimal 4.0.1, causing Gem::LoadError for bigdecimal 3.x #65
Description
Description
We received a customer report on the AWS SDK for Ruby repo aws-sdk-ruby#3273) about a bigdecimal version conflict on the Ruby 3.3 managed Lambda runtime.
In July 2025, the aws-sdk-core gem declares bigdecimal as a runtime dependency (with no version constraint). The runtime (ruby:3.3.mainline.v94) appears to pre-activate bigdecimal 4.0.1 as a default gem.
The stack trace contains no SDK or application frames: it's entirely Bundler and Lambda runtime code.
Could you take a look and let us know what the best path forward is?
Customer Context
{
"errorMessage": "You have already activated bigdecimal 4.0.1, but your Gemfile requires
bigdecimal 3.1.8. Prepending `bundle exec` to your command may solve this.",
"errorType": "Init<Gem::LoadError>",
"stackTrace": [
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/runtime.rb:328:in `check_for_activated_spec!'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/runtime.rb:25:in `block in setup'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/spec_set.rb:224:in `each'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/spec_set.rb:224:in `each'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/runtime.rb:24:in `map'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/runtime.rb:24:in `setup'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler.rb:165:in `setup'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/setup.rb:32:in `block in <top (required)>'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/ui/shell.rb:177:in `with_level'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/ui/shell.rb:122:in `silence'",
"/var/lang/lib/ruby/site_ruby/3.3.0/bundler/setup.rb:32:in `<top (required)>'",
"/var/runtime/gems/aws_lambda_ric-3.1.3/lib/aws_lambda_ric.rb:46:in `run'",
"/var/runtime/gems/aws_lambda_ric-3.1.3/lib/aws_lambda_ric.rb:219:in `bootstrap_handler'",
"/var/runtime/gems/aws_lambda_ric-3.1.3/lib/aws_lambda_ric.rb:201:in `start'",
"/var/runtime/index.rb:4:in `<main>'"
]
}
Managed zip. Here's the INIT line from the logs:
INIT_START Runtime Version: ruby:3.3.mainline.v94 Runtime Version ARN: arn:aws:lambda:us-east-1::runtime:58713c1f627a6d04dfda3ea4e11fae1cbca3ac46a4becad26f739c38911423d9
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benrkia commentedon Jun 19, 2026
Thanks for reporting this. This is a managed runtime issue, not a RIC issue, the RIC itself doesn't depend on bigdecimal or the AWS SDK.
The root cause is that the Ruby 3.3 managed runtime pre-installs
bigdecimal 4.x(pulled in as a transitive dependency ofaws-sdk-core). When the customer handler loadsbundler/setupit sees bigdecimal 4.x already activated but customer's Gemfile.lock requires 3.x causing theGem::LoadError.I'll be looking at this for the managed runtimes