Windows JRuby installs are broken

[chadlwilson]

Cross-posting from jdx/mise#8537 because there is no issues tab and not sure where else to look for possible assistance. I don't have the Rust experience to create a PR without AI-slopping it, and not sure it'll be correct by the design.

When you try and install jruby on Windows it ignores jruby and tries to install CRuby via RubyInstaller, which is not correct and cannot be intentional or the jruby- prefix shouldn't even resolve to a version on Windows.

Anyone got any idea where to start?

PS C:\Users\chad> mise use ruby@jruby-9
DEBUG Version: 2026.3.5 windows-arm64 (2026-03-07)
DEBUG ARGS: C:\Users\chad\scoop\apps\mise\current\bin\mise.exe use ruby@jruby-9
DEBUG [vfox] Getting metadata for yarn
DEBUG GET https://mise-versions.jdx.dev/tools/ruby.toml
DEBUG starting new connection: https://mise-versions.jdx.dev/
DEBUG connecting to 172.66.155.142:443
DEBUG connected to 172.66.155.142:443
DEBUG binding client connection
DEBUG client connection bound
DEBUG send frame=Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG Connection; peer=Client
DEBUG pooling idle connection for ("https", mise-versions.jdx.dev)
DEBUG received frame=Settings { flags: (0x0), max_concurrent_streams: 100, initial_window_size: 65536, max_frame_size: 16777215 }
DEBUG send frame=Settings { flags: (0x1: ACK) }
DEBUG received frame=WindowUpdate { stream_id: StreamId(0), size_increment: 2147418112 }
DEBUG send frame=WindowUpdate { stream_id: StreamId(0), size_increment: 5177345 }
DEBUG send frame=Headers { stream_id: StreamId(1), flags: (0x5: END_HEADERS | END_STREAM) }
DEBUG received frame=Settings { flags: (0x1: ACK) }
DEBUG received settings ACK; applying Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG received frame=Headers { stream_id: StreamId(1), flags: (0x4: END_HEADERS) }
DEBUG received frame=Data { stream_id: StreamId(1) }
DEBUG received frame=Data { stream_id: StreamId(1), flags: (0x1: END_STREAM) }
DEBUG GET https://mise-versions.jdx.dev/tools/ruby.toml 200 OK
INFO ruby@jruby-9.4.14.0 [1/3] install
INFO ruby@jruby-9.4.14.0 [1/3] downloading rubyinstaller-jruby-9.4.14.0-1-x64.7z
DEBUG GET Downloading https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-jruby-9.4.14.0-1/rubyinstaller-jruby-9.4.14.0-1-x64.7z to C:\Users\chad\AppData\Local\mise\downloads\ruby\jruby-9.4.14.0\rubyinstaller-jruby-9.4.14.0-1-x64.7z
DEBUG GET https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-jruby-9.4.14.0-1/rubyinstaller-jruby-9.4.14.0-1-x64.7z
DEBUG starting new connection: https://github.com/
DEBUG POST https://mise-versions.jdx.dev/api/track
DEBUG reuse idle connection for ("https", mise-versions.jdx.dev)
DEBUG send frame=Headers { stream_id: StreamId(3), flags: (0x4: END_HEADERS) }
DEBUG send frame=Data { stream_id: StreamId(3), flags: (0x1: END_STREAM) }
DEBUG connecting to 140.82.114.3:443
DEBUG connected to 140.82.114.3:443
DEBUG binding client connection
DEBUG client connection bound
DEBUG send frame=Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG Connection; peer=Client
DEBUG pooling idle connection for ("https", github.com)
DEBUG send frame=WindowUpdate { stream_id: StreamId(0), size_increment: 5177345 }
DEBUG send frame=Headers { stream_id: StreamId(1), flags: (0x5: END_HEADERS | END_STREAM) }
DEBUG received frame=Settings { flags: (0x0), max_concurrent_streams: 100, initial_window_size: 67108864, max_frame_size: 68608, enable_connect_protocol: 1 }
DEBUG send frame=Settings { flags: (0x1: ACK) }
DEBUG received frame=Settings { flags: (0x1: ACK) }
DEBUG received settings ACK; applying Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG received frame=Headers { stream_id: StreamId(1), flags: (0x4: END_HEADERS) }
DEBUG received frame=Data { stream_id: StreamId(1), flags: (0x1: END_STREAM) }
DEBUG GET https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-jruby-9.4.14.0-1/rubyinstaller-jruby-9.4.14.0-1-x64.7z 404 Not Found
Error:
0: Failed to install core:ruby@jruby-9: HTTP status client error (404 Not Found) for url (https://github.com/oneclick/rubyinstaller2/releases/download/RubyInstaller-jruby-9.4.14.0-1/rubyinstaller-jruby-9.4.14.0-1-x64.7z)
Location:
src\toolset\toolset_install.rs:230
Version:
2026.3.5 windows-arm64 (2026-03-07)
Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.