Cucumber crashes on Windows 11 with JRuby 10 when loading `sys-uname` through `jruby-win32ole`

[JoostVanAverbeke]

👓 What did you see?

We would like to use Cucumber on Windows 11 with JRuby 10.0 or later.
The Cucumber documentation currently lists JRuby 10.0+ as a supported platform, subject to some limitations.

Our project uses the following Gemfile:

source 'https://rubygems.org'

gem 'jruby-win32ole', '>= 0.8.5'
gem 'cucumber', '>= 11.1.1'

jruby-win32ole is required in our JRuby-based Windows environment.

When we start the Cucumber runner, the JVM crashes with the following native error:

# JRE version: OpenJDK Runtime Environment OpenLogic-OpenJDK
# (21.0.9+10)
#
# Java VM: OpenJDK 64-Bit Server VM OpenLogic-OpenJDK
# (21.0.9+10, mixed mode, sharing, tiered, compressed oops,
# compressed class ptrs, g1 gc, windows-amd64)
#
# Problematic frame:
# C  [racob-x64.dll+0x1aa4]
#
# No core dump will be written.
# Minidumps are not enabled by default on client versions of Windows.
#
# An error report file with more information is saved as:
# C:\Users\xxx\Documents\ADOWorkspace\JRubyWorkspace\
# try-jruby-cucumber\hs_err_pid7724.log

Investigation

I investigated why jruby-win32ole is loaded when starting Cucumber.

The dependency is introduced through the sys-uname gem. In the current Cucumber code, the operating-system version exposed by sys-uname is used by Cucumber::Runtime::MetaMessageBuilder#os:

def os
  Cucumber::Messages::Product.new(
    name: RbConfig::CONFIG['target_os'],
    version: Sys::Uname.version
  )
end

As far as I can determine, this operating-system metadata is the only Cucumber functionality that requires Sys::Uname.

In addition, lib/cucumber/runtime.rb requires sys/uname, although that file does not use Sys::Uname directly. Requiring it there causes the native Windows integration to be loaded during Cucumber startup.

On JRuby running on Windows, this ultimately loads racob-x64.dll, after which the JVM terminates with a native crash. Because this is a native JVM crash, it cannot be handled by rescuing a Ruby exception.

Proposed approach

Would you consider making the sys-uname integration optional on JRuby for Windows?

The unconditional require could be removed from:

lib/cucumber/runtime.rb

The dependency could then be loaded only where the operating-system metadata is built:

begin
  require 'sys/uname' unless RUBY_ENGINE == 'jruby' && Gem.win_platform?
rescue LoadError
  # sys-uname is optional. OS-version metadata will fall back
  # to a platform-independent value when it is unavailable.
end

The operating-system version could use a fallback when Sys::Uname is unavailable:

def os
  Cucumber::Messages::Product.new(
    name: RbConfig::CONFIG['target_os'],
    version: os_version
  )
end

def os_version
  return Sys::Uname.version if defined?(Sys::Uname)

  'unknown'
end

This preserves the existing sys-uname behavior on supported runtime and platform combinations, while avoiding the native jruby-win32ole code path on JRuby for Windows.

✅ What did you expect to see?

Cucumber should start successfully on Windows 11 with:

• JRuby 10.0 or later
• Java 21
• Cucumber 11.1.1 or later

If sys-uname cannot safely be loaded, Cucumber should still run and report a fallback operating-system version in its metadata.

Actual behavior

The JVM terminates while loading racob-x64.dll, before any Cucumber scenarios are executed.

📦 Which tool/library version are you using?

• jruby version = jruby 10.0.6.0 (3.4.5) 2026-06-11 716ad51f54 OpenJDK 64-Bit Server VM 21.0.9+10-adhoc.Administrator.jdk21u on 21.0.9+10-adhoc.Administrator.jdk21u +indy +jit [x86_64-mswin32]
• cucumber 11.1.1

🔬 How could we reproduce it?

No response

📚 Any additional context?

hs_err_pid7724.log