The JRuby community is pleased to announce the release of JRuby 10.1.2.0. * Homepage: [https://www.jruby.org/](https://www.jruby.org/) * Download: [https://www.jruby.org/download](https://www.jruby.org/download) JRuby 10.1.x targets Ruby 4.0 compatibility. Thank you to our contributors this release, you help keep JRuby moving forward! [@aminmansuri], [@drzaiusx11], [@evaniainbrooks], [@gillesbergerp], [@jcharaoui], [@jwils], [@kares], [@lloeki], [@makenowjust], [@nobu], [@sampokuokkanen], [@shugo] Notable Changes --------------- ### Compatibility * Multiple fixes for fibers and fiber scheduler support. [#9604], [#9607], [#9622], [#9645], [#9649], [#9656], [#9660] ### Performance * Fixed a regression in startup time on MacOS by properly loading native JNR subsystem. [#9690] * Improve performance of Ruby subclasses of Java classes. [#9619], [#9557] * Improve performance of autoloads overridden by an actual require. [#9677] ### Java Integration * The location of the AppCDS JSA file can now be specified with JRUBY_JSA_HOME. [#9667] ### Standard Library * Update to jar-dependencies 0.6.1 using mima for dependency resolution instead of the ruby-maven gem. [#9515], [#9720] * Update default and bundled standard library gems. [#9705] #### Default gems * erb 6.0.7 * error_highligh 0.7.2 * ffi 1.17.4 * io-console 0.9.4 * ipaddr 1.2.9 * jruby-openssl 0.16.2 * json 2.21.2 * net-protocol 0.4.0 * pp 0.6.4 * psych 5.5.0 * resolv 0.8.0 * strscan 3.1.8 * syntax_suggest 3.0.0 * timeout 0.6.1 * win32-registry 0.1.2 #### Bundled gems * bigdecimal 4.1.2 (ruby parts only) * csv 3.3.6 * minitest 5.27.0 * net-imap 0.6.7 * nkf 0.3.0 * pstore 0.2.1 * rdoc 7.2.0 * reline 0.7.0 * resolv-replace 0.2.0 * rss 0.3.3 * test-unit 3.7.8 ### 76 Issues and PRs resolved for 10.1.2.0 https://www.jruby.org/2026/09/21/jruby-10-1-2-0 *Charles Oliver Nutter* *Architect and Technologist* Headius Enterprises https://www.headius.com headius@headius.com