Ruby LSP extension not activating on Apple Silicon (M4, Rosetta, rbenv, Ruby 3.3.5)

[Prabodh-Panda]

Description:
I'm unable to get the Ruby LSP extension working in VS Code on my Apple Silicon M4 MacBook (running under Rosetta). The activation script runs successfully, but the LSP server fails to start. I've tried all troubleshooting steps from the documentation and previous issues, but nothing resolves the problem.

System Information:

• Mac: Apple Silicon M4 (with Rosetta)
• OS: macOS 15.5
• VS Code: 1.102.0
• Ruby version: 3.3.5 (via rbenv)
• Ruby LSP extension: v0.9.28
• ruby-lsp gem: Installed for Ruby 3.3.5
• Shell: zsh

What I tried:

• Verified rbenv and Ruby version in VS Code terminal
• Ensured activation.rb is executable
• Installed/updated ruby-lsp gem for the correct Ruby version
• Removed/reinstalled the extension and the gem
• Launched VS Code from terminal to inherit shell environment
• Restarted VS Code and machine multiple times

Logs and Output:

Activation script output (manual run):

/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'
RUBY_LSP_ACTIVATION_SEPARATOR3.3.5RUBY_LSP_FS/Users/prabodh/.local/share/gem/ruby/3.3.0,...
RUBY_LSP_ACTIVATION_SEPARATOR%

VS Code Ruby LSP Output Channel:

2025-07-11 12:12:02.174 [info] (blog-it) Found rbenv executable at /usr/local/bin
2025-07-11 12:12:02.175 [info] (blog-it) Running command: `/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'` in /Users/prabodh/pixelcompute/blog-it using shell: /usr/bin/arch
2025-07-11 12:12:02.178 [info] (blog-it) Running command: `/usr/bin/ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'` in /Users/prabodh/pixelcompute/blog-it using shell: /usr/bin/arch
2025-07-11 12:18:13.977 [info] (blog-it) Restarting the Ruby LSP because configuration changed
2025-07-11 12:18:13.983 [info] (blog-it) Found rbenv executable at /usr/local/bin
2025-07-11 12:18:13.985 [info] (blog-it) Running command: `/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'` in /Users/prabodh/pixelcompute/blog-it using shell: /usr/bin/arch
2025-07-11 12:19:37.248 [info] (blog-it) Found rbenv executable at /usr/local/bin
2025-07-11 12:19:37.248 [info] (blog-it) Running command: `/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'` in /Users/prabodh/pixelcompute/blog-it using shell: /usr/bin/arch

Expected behavior:
Ruby LSP extension activates and provides language server features in VS Code.

Actual behavior:
I get the following error on start up

Automatic Ruby environment activation with rbenv failed: Command failed: /usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb' arch: /usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb' isn't executable

Additional context:

• No other Ruby managers (rvm, chruby) installed.
• No conflicting VS Code extensions.
• This occurs even in a minimal, new Ruby project.
• All environment variables appear correct; ruby-lsp gem is installed and available.

Steps to reproduce:

1. Use Apple Silicon M4 MacBook (Rosetta)
2. Install Ruby 3.3.5 with rbenv
3. Install latest Ruby LSP extension in VS Code
4. Open any Ruby project

Request:
Please advise on further debugging steps, or let me know if this is a known compatibility issue with M4/Rosetta or Ruby 3.3.5. Happy to provide more logs or run additional diagnostics.

[vinistock]

Thank you for the report. Based on the error message, something in the shell command that the extension runs to activate the Ruby environment is not executable (for some reason).

If you try to run activation manually in your shell, does it print a bunch of environment variables or does it crash?

/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'

It looks like the message is coming from your shell (/usr/bin/arch), so it might be some intersection of that shell, rbenv and the extension.

[Prabodh-Panda]

Thank you for the report. Based on the error message, something in the shell command that the extension runs to activate the Ruby environment is not executable (for some reason).

If you try to run activation manually in your shell, does it print a bunch of environment variables or does it crash?

/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.28/activation.rb'
It looks like the message is coming from your shell (/usr/bin/arch), so it might be some intersection of that shell, rbenv and the extension.

Yes it does print a bunch of environment variables. I tried running the activation manually on the integrated terminal as well and it prints out the same output.

[Prabodh-Panda]

The extension functions correctly when the default terminal is set to zsh using:

"terminal.integrated.defaultProfile.osx": "zsh"

However, the issue arises when rosetta is set as the default terminal — the error mentioned above occurs in that case.

[vinistock]

Okay, so it's definitely some intersection between the shell and VS Code. I'm not sure what causes the difference when invoking the shell through NodeJS.

It will be hard to fix without a bit more information. If you're up for debugging this a bit more, here is where we ultimately invoke the shell using exec. We need to understand why invoking your shell through NodeJS fails when doing it manually in the terminal does not.

[Prabodh-Panda]

I wrote the following script

const { exec } = require('child_process');
exec("/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.29/activation.rb'", {
  shell: '/bin/zsh',
  env: process.env,
  encoding: 'utf-8'
}, (err, stdout, stderr) => {
  console.log({ err, stdout, stderr });
});

And the output contained the environment variables in stderr instead of stdout. This might be the cause of the error?

[vinistock]

That shouldn't be a problem. The error message says that rbenv is not executable. If it's successfully printing to stderr, then it's doing the expected behaviour.

Does that script also work then the shell is /usr/bin/arch instead of zsh?

[Prabodh-Panda]

That shouldn't be a problem. The error message says that rbenv is not executable. If it's successfully printing to stderr, then it's doing the expected behaviour.

Does that script also work then the shell is /usr/bin/arch instead of zsh?

No it doesn't work. It throws the following error

{
  err: Error: Command failed: /usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.29/activation.rb'
  arch: /usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.29/activation.rb' isn't executable
  
      at genericNodeError (node:internal/errors:983:15)
      at wrappedFn (node:internal/errors:537:14)
      at ChildProcess.exithandler (node:child_process:414:12)
      at ChildProcess.emit (node:events:524:28)
      at maybeClose (node:internal/child_process:1101:16)
      at ChildProcess._handle.onexit (node:internal/child_process:304:5) {
    code: 1,
    killed: false,
    signal: null,
    cmd: "/usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.29/activation.rb'"
  },
  stdout: '',
  stderr: "arch: /usr/local/bin/rbenv exec ruby -EUTF-8:UTF-8 '/Users/prabodh/.vscode/extensions/shopify.ruby-lsp-0.9.29/activation.rb' isn't executable\n"
}

[vinistock]

Okay, so that's definitely the issue. I'm not familiar with using arch as a shell, so I don't know why this happens. If we can understand in detail why this happens and how to fix, we can look into pushing a fix for it.

If arch simply cannot be invoked from Node, then we could intentionally unset the shell in that case, but we need to first confirm if this is an intrinsic characteristic of arch and not some configuration issue.

[Prabodh-Panda]

I'm also not very familiar with Arch, so I'm not entirely sure if this is expected behaviour or a configuration-specific issue. Let me know if there's anything else I can provide to help move things forward.