Breaking change on GemfileNotFound behavior on 4.0.1

[roger-zhangg]

Description

In Bundler 4.0.1, a breaking change was introduced in how GemfileNotFound errors are handled. Previously, when a Gemfile was not found, Bundler would exit with status code 10. However, in 4.0.1, if the invoke_other_command("cli_help") call fails during the error handling, a different exit code is returned due to the NoMethodError, breaking the expected behavior.

Current Behavior

When running bundle commands without a Gemfile present:

GemfileNotFound error is caught
invoke_other_command("cli_help") is called
If cli_help fails (as shown in the error log with NoMethodError), the original GemfileNotFound error is thrown later and its exit code 10 are lost
Instead, a NoMethodError is raised first with a different exit code

Expected Behavior

Even if the help command fails, Bundler should maintain the original GemfileNotFound error and exit code 10 to preserve backward compatibility and expected behavior.

Error Log

NoMethodError: undefined method `[]' for nil:NilClass
  C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:107:in `block in cli_help'
  ...

Relevant Code

#9164

https://github.com/eregon/rubygems/blob/979dada8f39999191f23cd0ded6191aff57e093f/bundler/lib/bundler/cli.rb#L293-L295

Environment

Bundler: 4.0.1
Ruby: 3.2.9p265
Platform: x64-mingw-ucrt

Suggested Fix

Consider one of these approaches:

Ensure cli_help doesn't fail when handling GemfileNotFound
Wrap the invoke_other_command in a begin/rescue block to preserve the original error
Remove the help command invocation for this specific error case

This is a breaking change as it affects tools and scripts that rely on the exit code 10 for GemfileNotFound errors.

[hsbt]

This seems duplicate with #9165

[roger-zhangg]

Thanks @hsbt ,this seems different. This seems only happening on windows. We didn't observe the behavior on 4.0.0. We have a workflow which expect Bundler to throw GemfileNotFound error and we have a handling method to take over. However since 4.0.1, Bundler on windows starts throwing the NoMethodError: undefined method '[]' for nil:NilClass on GemfileNotFound scenarios. And changed the exit code to 1. (which used to be 10 - GemfileNotFound)

[hsbt]

Can you try the following and share them?

• ruby -rbundler -e'p Bundler::CLI.printable_commands(true)'
• bundle cli_help

[reedham-aws]

Working with @roger-zhangg, these are the results:

ruby -rbundler -e'p Bundler::CLI.printable_commands(true)'

[["-e help [COMMAND]", "# Describe available commands or one specific command"], ["-e init [OPTIONS]", "# Generates a Gemfile into the current working directory"], ["-e check [OPTIONS]", "# Checks if the dependencies listed in Gemfile are satisfied by currently installed gems"], ["-e remove [GEM [GEM ...]]", "# Removes gems from the Gemfile"], ["-e install [OPTIONS]", "# Install the current environment to the system"], ["-e update [OPTIONS]", "# Update the current environment"], ["-e show GEM [OPTIONS]", "# Shows all gems that are part of the bundle, or the path to a given gem"], ["-e list", "# List all gems in the bundle"], ["-e info GEM [OPTIONS]", "# Show information for the given gem"], ["-e binstubs GEM [OPTIONS]", "# Install the binstubs of the listed gem"], ["-e add GEM VERSION", "# Add gem to Gemfile and run bundle install"], ["-e outdated GEM [OPTIONS]", "# List installed gems with newer versions available"], ["-e fund [OPTIONS]", "# Lists information about gems seeking funding assistance"], ["-e cache [OPTIONS]", "# Locks and then caches all of the gems into vendor/cache"], ["-e exec [OPTIONS]", "# Run the command in context of the bundle"], ["-e config NAME [VALUE]", "# Retrieve or set a configuration value"], ["-e open GEM", "# Opens the source directory of the given bundled gem"], ["-e console [GROUP]", "# Opens an IRB session with the bundle pre-loaded"], ["-e version", "# Prints Bundler version information"], ["-e licenses", "# Prints the license of all gems in the bundle"], ["-e gem NAME [OPTIONS]", "# Creates a skeleton for creating a rubygem"], ["-e clean [OPTIONS]", "# Cleans up unused gems in your bundler directory"], ["-e platform [OPTIONS]", "# Displays platform compatibility information"], ["-e lock", "# Creates a lockfile without installing"], ["-e env", "# Print information about the environment Bundler is running under"], ["-e doctor [OPTIONS]", "# Checks the bundle for common problems"], ["-e issue", "# Learn how to report an issue in Bundler"], ["-e pristine [GEMS...]", "# Restores installed gems to pristine condition"], ["-e plugin", "# Manage the bundler plugins"]]

bundle cli_help

Bundler version 4.0.1 (2025-12-09 commit f3e5ebf5af)

Bundler commands:

  Primary commands:
    bundle install [OPTIONS]    # Install the current environment to the system
    bundle update [OPTIONS]     # Update the current environment
    bundle cache [OPTIONS]      # Locks and then caches all of the gems into ...
    bundle exec [OPTIONS]       # Run the command in context of the bundle
    bundle config NAME [VALUE]  # Retrieve or set a configuration value
    bundle help [COMMAND]       # Describe available commands or one specific...

  Utilities:
    bundle add GEM VERSION         # Add gem to Gemfile and run bundle install
    bundle binstubs GEM [OPTIONS]  # Install the binstubs of the listed gem
    bundle check [OPTIONS]         # Checks if the dependencies listed in Gem...
    bundle clean [OPTIONS]         # Cleans up unused gems in your bundler directory
    bundle console [GROUP]         # Opens an IRB session with the bundle pre-loaded
    bundle doctor [OPTIONS]        # Checks the bundle for common problems
    bundle env                     # Print information about the environment ...
    bundle fund [OPTIONS]          # Lists information about gems seeking fun...
    bundle gem NAME [OPTIONS]      # Creates a skeleton for creating a rubygem
    bundle info GEM [OPTIONS]      # Show information for the given gem
    bundle init [OPTIONS]          # Generates a Gemfile into the current wor...
    bundle issue                   # Learn how to report an issue in Bundler
    bundle licenses                # Prints the license of all gems in the bundle
    bundle list                    # List all gems in the bundle
    bundle lock                    # Creates a lockfile without installing
    bundle open GEM                # Opens the source directory of the given ...
    bundle outdated GEM [OPTIONS]  # List installed gems with newer versions ...
    bundle platform [OPTIONS]      # Displays platform compatibility information
    bundle plugin                  # Manage the bundler plugins
    bundle pristine [GEMS...]      # Restores installed gems to pristine condition
    bundle remove [GEM [GEM ...]]  # Removes gems from the Gemfile
    bundle show GEM [OPTIONS]      # Shows all gems that are part of the bund...
    bundle version                 # Prints Bundler version information
  
  Options:
        [--no-color]                                   # Disable colorization in output
    -r, [--retry=NUM]                                  # Specify the number of times you wish to attempt network commands
    -V, [--verbose], [--no-verbose], [--skip-verbose]  # Enable verbose output mode

[hsbt]

It's strange result if they worked with on Windows.

[reedham-aws]

Just to be clear, it did not work on Windows. The issue is that on Windows only, the return code for GemfileNotFound is being overwritten with a code of 1, which is presumably the result of cli_help. This is breaking because although Bundler is correctly determining there's no Gemfile, it's not returning the error code that is established for that, which we are expecting in our code.

[hsbt]

I plan to fix cli_help if it doesn't work. Again, can you share the result of following command with Windows especially the same environment that initial issue is happend?

• ruby -rbundler -e'p Bundler::CLI.printable_commands(true)'
• bundle cli_help

[Edouard-chin]

We have a workflow which expect Bundler to throw GemfileNotFound

Are you invoking bundler the normal way using the bundle executable, or do you programatically use the Bundler::CLI in another program ? Asking because that could explain why it breaks due to Thor that relies on the $PROGRAM_NAME

rubygems/bundler/lib/bundler/vendor/thor/lib/thor/base.rb

Line 772 in 570c341

File.basename($PROGRAM_NAME).split(" ").first

which would break the regex here

rubygems/bundler/lib/bundler/cli.rb

Line 107 in 570c341

by_name = list.group_by {|name, _message| name.match(/^bundle (\w+)/)[1] }

[reedham-aws]

We are invoking by using the bundle executable from python via subprocess.Popen (relevant code here).

The result I posted above is the results from the same environment with the exact commands. I'm not very familiar with Windows environments, but I'm wondering if the issue is related to the fact that in our code we call bundler.bat as the executable for Windows. bundler.bat cli_help returns the following error:

--- ERROR REPORT TEMPLATE -------------------------------------------------------

NoMethodError: undefined method `[]' for nil:NilClass
  C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:107:in `block in cli_help'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:107:in `each'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:107:in `group_by'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:107:in `cli_help'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/vendor/thor/lib/thor/command.rb:28:in `run'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/vendor/thor/lib/thor.rb:538:in `dispatch'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:35:in `dispatch'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/vendor/thor/lib/thor/base.rb:584:in `start'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/cli.rb:29:in `start'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/exe/bundle:28:in `block in <top (required)>'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/lib/bundler/friendly_errors.rb:118:in `with_friendly_errors'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/exe/bundle:20:in `<top (required)>'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/exe/bundler:4:in `load'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0/gems/bundler-4.0.1/exe/bundler:4:in `<top (required)>'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/bin/bundler:32:in `load'
          C:/hostedtoolcache/windows/Ruby/3.2.9/x64/bin/bundler:32:in `<main>'


## Environment

Bundler       4.0.1
  Platforms   ruby, x64-mingw-ucrt
Ruby          3.2.9p265 (2025-07-24 revision 8f611e0c46012e321b39efd629eb5f4f53976863) [x64-mingw-ucrt]
  Full Path   C:/hostedtoolcache/windows/Ruby/3.2.9/x64/bin/ruby.exe
  Config Dir  C:/ProgramData
RubyGems      3.4.19
  Gem Home    C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0
  Gem Path    C:/Users/runneradmin/.local/share/gem/ruby/3.2.0;C:/hostedtoolcache/windows/Ruby/3.2.9/x64/lib/ruby/gems/3.2.0
  User Home   C:/Users/runneradmin
  User Path   C:/Users/runneradmin/.local/share/gem/ruby/3.2.0
  Bin Dir     C:/hostedtoolcache/windows/Ruby/3.2.9/x64/bin
Tools         
  Git         2.52.0.windows.1
  RVM         not installed
  rbenv       not installed
  chruby      not installed
Gem.ruby      C:/hostedtoolcache/windows/Ruby/3.2.9/x64/bin/ruby.exe
bundle #!     /bin/sh


## Bundler Build Metadata

Timestamp  2025-12-09
Git SHA    f3e5ebf5af

--- TEMPLATE END ----------------------------------------------------------------

[Edouard-chin]

Thanks for adding more information.

Re bundle.bat, that's what I thought too, but I can't seem to reproduce the NoMethodError problem

https://github.com/Edouard-chin/experiment/actions/runs/20238418737/job/58099357773

I'll look a bit more

[Edouard-chin]

Oh! I just saw "bundler.bat" with a "r" at the end. Yeah that's the issue.

But I think this needs to be fixed in Bundler so that we dont rely on hardcoded "bundle". I'll open a fix

[Edouard-chin]

Also FWIW, it's not a windows specific issue. Calling bundler install will fail the same way on any platform

[reedham-aws]

So just to confirm, the issue is as follows:

1. A change was added in 4.0.1 to add cli_help behavior to GemfileNotFound cases.
2. bundler.bat as an executable cannot find cli_help specifically, leading to the NoMethodError (I confirmed that bundle.bat works as expected.
3. The issue is that cli_help depends on a hardcoded "bundle" string.

I will do some testing to see if changing to bundle.bat in our code will result change the behavior.

[reedham-aws]

I have confirmed that bundle.bat as the executable (instead of bundler.bat) fixed the issue. I don't quite understand why bundler.bat has been working previously and in other cases.