rbenv Ruby 3.0.6 "cannot load such file -- socket"

[roloand]

I'm on a new Mac: M5 Pro, OS Tahoe 26.4. Installed rbenv fresh, and installed ruby 3.0.6 with it, using a patch as outlined in other threads. For the record, these are the commands I used:

brew install rbenv/tap/openssl@1.1
brew link --overwrite openssl@1.1
curl -fsSL https://github.com/ruby/ruby/commit/1dfe75b0beb7171b8154ff0856d5149be0207724.patch | rbenv install 3.0.6 --patch

Ruby 3.0.6 is installed successfully. However, when trying gem install bundler or just try to do anything, I get the following error (including stack trace that comes up when I try bundle install):

<internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- socket (LoadError)
        from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/net/protocol.rb:22:in `<top (required)>'
        from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/net/http.rb:23:in `<top (required)>'
from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
        from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendor/net-http-persistent/lib/net/http/persistent.rb:1:in `<top (required)>'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendored_persistent.rb:11:in `require_relative'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendored_persistent.rb:11:in `<top (required)>'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/fetcher.rb:3:in `require_relative'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/fetcher.rb:3:in `<top (required)>'
        from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
from <internal:/Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/cli/install.rb:48:in `run'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/cli.rb:253:in `block in install'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/settings.rb:131:in `temporary'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/cli.rb:252:in `install'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/cli.rb:31:in `dispatch'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/cli.rb:25:in `start'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/gems/3.0.0/gems/bundler-2.2.33/libexec/bundle:49:in `block in <top (required)>'
from /Users/username/.rbenv/versions/3.0.6/lib/ruby/3.0.0/bundler/friendly_errors.rb:103:in `with_friendly_errors'
        from /Users/username/.rbenv/versions/3.0.6/lib/ruby/gems/3.0.0/gems/bundler-2.2.33/libexec/bundle:37:in `<top (required)>'
from /Users/username/.rbenv/versions/3.0.6/bin/bundle:23:in `load'
        from /Users/username/.rbenv/versions/3.0.6/bin/bundle:23:in `<main>'

I tried installing and using 3.1.0 on a separate directory and installing bundler and I'm getting the same error. I also ran the rbenv_doctor script and it didn't diagnose any issues. I'd appreciate any help with this, as I've been at it by myself for a whole day. Thanks!

[mislav]

Hi, since this is not a bug with rbenv, but a build failure in Ruby's own build system, I've converted this to a Discussion in the ruby-build repository.

First of all, I can reproduce this on macOS 26.2 when attempting to install both Ruby 3.0.6 and the latest 3.0.x version, Ruby 3.0.7:

$ curl -fsSL https://github.com/ruby/ruby/commit/1dfe75b0beb7171b8154ff0856d5149be0207724.patch | \
  rbenv install 3.0 --force --keep --patch -- --with-ext=socket,+

Some notes:

• --force makes it so that rbenv will try to re-install the Ruby version even if one exists already (but has broken socket extension);
• --keep keeps the original Ruby source tree on disk even after a successful build so you can inspect individual log files (normally only the main build log is kept, but that one doesn't always contain all the information);
• --with-ext=socket,+ passed as a ruby configure flag will ensure that the overall build fails if the "socket" extension fails to build (without that, the build would succeed, but network-related Ruby functionality would not work).

I get this output:

*** Following extensions are not compiled:
gdbm:
        Could not be configured. It will not be installed.
        Check /Users/mislav/.rbenv/sources/3.0.7/ruby-3.0.7/ext/gdbm/mkmf.log for more details.
socket:
        Could not be configured. It will not be installed.
        /Users/mislav/.rbenv/sources/3.0.7/ruby-3.0.7/ext/socket/extconf.rb:660: No such file or directory @ rb_sysopen - /usr/include/netinet6/in6.h
        Check /Users/mislav/.rbenv/sources/3.0.7/ruby-3.0.7/ext/socket/mkmf.log for more details.

BUILD FAILED (macOS 26.2 on arm64 using ruby-build 20260512)

You can inspect the build directory at /Users/mislav/.rbenv/sources/3.0.7
See the full build log at /var/folders/6k/fwzzx67n163b0lfftyw3313h0000gn/T/ruby-build.20260515165014.31269.log

We can see that "socket" extension failed to compile, and now the build is properly aborted. The reason why the extension failed to compile might be in the extension's own log, which I'm uploading here: https://gist.github.com/mislav/46a5082b48f42938e41632f4f165b9c9

This log file is hard to read because it contains everything that Ruby attempted to test during "socket" extension compilation, and that may include warnings and errors that were non-fatal. In fact, by casually scanning this log file I can't detect what exactly is the cause of the error, but I know for a fact that Ruby 3.0 was able to compile using an older version of macOS. This might be an example of an issue that stems from newer macOS changing some of its libraries and APIs, and older Rubies become incompatible with the OS due to their EoL (End-of-Life) status. You may be able to find another patch to apply to this Ruby version, but instead I'd strongly advise you to upgrade your project to a Ruby version that compiles on your system.

Finally, do NOT do brew link --overwrite openssl@1.1 on your system. You might have seen it suggested as a workaround by the community, but later on it can cause more harm to your other software than it benefits here. Run brew unlink openssl@1.1 to fix.

[mislav]

The RString problem seems to have been fixed in Ruby 3.2, but I'm not clear on whether that patch applies cleanly to Ruby 3.0. (It looks to me like it doesn't.) You may have more luck if you start investigating from here: ruby/ruby@357d601

[roloand]

@mislav thanks for the info, I really appreciate it. I'll take a look at the link provided. I did try with Ruby 3.2 afterwards and that installation worked well. If I can't find anything else that could be a fix for this, I'll have to upgrade. Thanks again!

[unurgunite]

I found a workaround for Ruby 3.0.x / 3.1.x on macOS 26 (Tahoe) — missing /usr/include/netinet6/in6.h

Ruby 3.0 and 3.1 are EoL and their ext/socket/extconf.rb hardcodes File.read("/usr/include/netinet6/in6.h") at build time. macOS 26 no longer has /usr/include/ — system headers are inside the SDK only.

I created two gist patches that fix this:

• Ruby 3.0.x (includes BigDecimal maybe_unused fix + socket SDK path fix):

  curl -fsSL https://gist.githubusercontent.com/unurgunite/4d6f9ecade222d9f5c6f6e8503ffdc38/raw/1dd825494ba945b3cc40bf2d2bfe9c6817327448/ruby-3.0-macos26.patch | RUBY_CONFIGURE_OPTS="--enable-yjit --with-jemalloc2" rbenv install 3.0.7 --force --patch -- --with-ext=socket,+

• Ruby 3.1.x (socket SDK path fix only — BigDecimal already fixed):

  curl -fsSL https://gist.githubusercontent.com/unurgunite/4d6f9ecade222d9f5c6f6e8503ffdc38/raw/1dd825494ba945b3cc40bf2d2bfe9c6817327448/ruby-3.1-macos26.patch | RUBY_CONFIGURE_OPTS="--enable-yjit --with-jemalloc2" rbenv install 3.1.7 --force --patch -- --with-ext=socket,+

Replace the version number (3.0.7 / 3.1.7) with whichever patch version you need.

After install, verify:

ruby -e "require 'socket'; puts Socket::AF_INET6" #=> 30

And as @mislav already noted above — do not run brew link --overwrite openssl@1.1, it can break other software on your system.
CC @roloand

[roloand]

@unurgunite Thanks! That worked great. This'll give me more time to move the app off 3.0.6. I really appreciate your help.

[unurgunite]

Glad to help!

[mislav]

Awesome; thanks for the investigative work and for the patches! 🚀

[manas-ashwin]

This worked. Thank you so much 🙏 🙇

[NickRycar]

Thank you from the future.

Signed, a dude playing with an old repo that doesn't want to update a sample app.

[kliuless]

For me, the missing include file was a red herring for ruby 3.1.7.
Note also that openssl 3 seems to work fine.

Using this env var worked without patches:

CFLAGS="-isysroot $(xcrun --show-sdk-path) -Wno-default-const-init-field-unsafe"

The key is the -Wno-default-const-init-field-unsafe (not sure if the sysroot was necessary).

Explanation (AI-generated):

Socket fails because:

• Your clang has a new diagnostic, -Wdefault-const-init-field-unsafe, that fires inside Ruby 3.1.7's rstring.h (the const VALUE klass field).
• The socket extconf.rb runs an IN6_IS_ADDR_UNSPECIFIED probe with -Werror. That warning becomes a fatal error, so the probe fails — for a reason unrelated to networking.
• The extconf misinterprets the failure as "Apple's in6.h is broken," tries to read the hardcoded /usr/include/netinet6/in6.h (which doesn't exist on modern macOS — headers are in the SDK), and crashes. ruby-build doesn't treat a crashed optional extension as fatal, so the install "succeeds" with no socket.bundle.