The JRuby community is pleased to announce the release of JRuby 10.1.1.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.1.1.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @chadlwilson, @kares, @katafrakt, @sampokuokkanen, @segiddins, @shugo

Notable Changes

Performance

• Use FastDoubleParser to improve performance of all string-to-double parsing. #9150
• Only pack fixnum values for 16-bit signed by default, with optional 8-bit and 32-bit configs. #9379

Standard Library

• jruby-openssl updated to 0.16.2 with several CVE fixes from BouncyCastle. #9386, #9504, #9539
• erb updated to 6.0.1.1 to address CVE-2026-41316. #9388

Native Integration

• Updated JRuby's native library backend with support for OpenBSD. #9439

Java Integration

• Optimized automatic interface implementation when calling Java with a block. #5023

Packaging

• Begin deprecating jruby-complete and jruby-core Maven artifacts. Prefer the jruby and jruby-base artifacts. #9512

57 Issues and PRs resolved for 10.1.1.0

• #5023 excessive loading of same InterfaceImpl
• #8184 remove deprecated (internal) Java code
• #9034 unused variable warning for blocks
• #9061 Ruby 4.0 support
• #9150 Use FastDoubleParser where appropriate
• #9219 True keyword arguments
• #9320 Cannot run code that has large Integer in when clause
• #9375 instance_exec block argument destructuring when default value passed
• #9376 Fix destructuring of block argument with default value
• #9379 Make fixnum packing configurable and disable ints
• #9381 Shrink RubyHashLinkedBuckets
• #9386 [deps] bump jruby-openssl to 0.16.0
• #9388 deps(stdlib): bump erb from 6.0.1 to 6.0.1.1 to resolve CVE-2026-41316
• #9393 [10.1.0.0] Java::JavaLang::IllegalArgumentException: argument type mismatch
• #9395 Difference in what caller returns in JRuby 10.1 and Ruby 4.0
• #9396 Remove Class#new from backtrace
• #9398 JRuby 10.1 circular causes failures within nested rescue (e.g rspec's tests)
• #9400 Don't warn about unused destructured block/method parameters (GH-9034)
• #9404 Warn on class/const assign in condition
• #9405 Marshal.load corrupts repeated object reference after Set appears earlier in payload
• #9407 Refactor Kernel#raise and fix remaining specs
• #9408 Fix last send_spec with correct message
• #9409 Ensure core exceptions get raised with $! as cause
• #9410 Fix Hash#inspect of Symbol keys with non-ASCII encoding
• #9417 Checking out aws-sdk-ruby creates a file with binary data.
• #9418 Fix recursive set marshal dump and load
• #9420 Fix Method/UnboundMethod#original_name deep alias chains
• #9425 ivarSet missing return after megamorphic fallback
• #9427 regression for activerecord-jdbcsqlite3-adapter: java.lang.NoSuchMethodError: 'void org.jruby.RubyHash.(org.jruby.Ruby, int)'
• #9435 Fall back to standard case/when for out-of-int-range Fixnum literals (#9320)
• #9437 Pathname provides differing error message from MRI in JRuby 10.1.0.0
• #9439 Update jffi for aarch64 OpenBSD
• #9442 Use proper error text for nulls in path name
• #9445 Reject invalid $0-prefixed global variable names like $01, $0abc
• #9447 Improve alias redefinition warnings
• #9450 Reverse aliasing warns when it should not
• #9456 Restore RubyHash(Ruby, int) for older ARJDBC versions
• #9459 [fix] rename RubyHash#set(get) to avoid collision
• #9462 Regression in JRuby 10.1 with Prawn
• #9470 Clean up more divergent keyword logic
• #9473 Shade redline to avoid conflicting with external versions
• #9488 Support backtrace_locations with Java exceptions
• #9495 No need to check for virtual thread API availability
• #9501 Fix CALL_KEYWORD_EMPTY leaking from (...) forwards to native methods
• #9503 avoid setting $! from RaiseException
• #9504 [deps] bump jruby-openssl to 0.16.1
• #9511 Update jnr:* and asm to latest
• #9512 Begin deprecating jruby-complete and jruby-core
• #9520 defined?(...) in eval'd for loop fails with TypeError
• #9523 Don't copy the singleton class in Proc#dup
• #9539 Update jruby-openssl to 0.16.2
• #9540 Merge 10.0
• #9541 NoMatchingPatternError#=== doesn't match instance of NoMatchingPatternKeyError
• #9543 Time.new(string, in: ...) raises TypeError on the third call at a call site (JIT only)
• #9545 Add a warning for nonuniform keywords annotations
• #9546 Prism backend raises wrong error for pattern key mismatch
• #9547 Merge jruby-prism fix for NoPatternKeyError