cannot load such file -- exception_notification (LoadError)

Question

cannot load such file -- exception_notification (LoadError)

1.1k Views Asked by e-e At 05 April 2025 at 04:30

I'm attempting to send exceptions to a slack channel. This was my set up:

Added the following to my Gemfile

gem 'exception_notification'
gem 'slack-notifier'

Created a new initializer config/initializers/errors.rb

# Works in development with or without this require
require 'exception_notification'

Rails.application.config.middleware.use(
    ExceptionNotification::Rack,
    :slack => {
        :webhook_url => ENV["SLACK_ERROR_WEBHOOOK_URL"]
    }
)

I have rebuilt my docker images and deleted the gem cache volumes.

This works properly in my development environment (errors get sent to slack), but isn't working on my production server. The only real difference that I can think of between the two is the RAILS_ENV value, at least configuration-wise. I'm fairly new to Rails however, as well as deploying to a production environment.

Immediately upon starting the app (docker-compose up) it exits with the following error:

/usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:34:in `require': cannot load such file -- exception_notification (LoadError)
app_1           |   from /usr/local/bundle/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `block in require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:291:in `load_dependency'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `require'
app_1           |   from /app/config/initializers/errors.rb:1:in `<main>'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:55:in `load'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:55:in `load'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:319:in `block in load'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:291:in `load_dependency'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:319:in `load'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/engine.rb:667:in `block in load_config_initializer'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/notifications.rb:182:in `instrument'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/engine.rb:666:in `load_config_initializer'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/engine.rb:624:in `block (2 levels) in <class:Engine>'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/engine.rb:623:in `each'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/engine.rb:623:in `block in <class:Engine>'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:32:in `instance_exec'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:32:in `run'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:61:in `block in run_initializers'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:228:in `block in tsort_each'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:422:in `block (2 levels) in each_strongly_connected_component_from'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:431:in `each_strongly_connected_component_from'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:421:in `block in each_strongly_connected_component_from'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:50:in `each'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:50:in `tsort_each_child'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:415:in `call'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:415:in `each_strongly_connected_component_from'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:349:in `block in each_strongly_connected_component'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:347:in `each'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:347:in `call'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:347:in `each_strongly_connected_component'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:226:in `tsort_each'
app_1           |   from /usr/local/lib/ruby/2.6.0/tsort.rb:205:in `tsort_each'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/initializable.rb:60:in `run_initializers'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/application.rb:363:in `initialize!'
app_1           |   from /app/config/environment.rb:5:in `<main>'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
app_1           |   from /usr/local/bundle/gems/zeitwerk-2.3.0/lib/zeitwerk/kernel.rb:23:in `require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `block in require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:291:in `load_dependency'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `require'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:49:in `require_relative'
app_1           |   from config.ru:3:in `block in <main>'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/builder.rb:116:in `eval'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/builder.rb:116:in `new_from_string'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/builder.rb:105:in `load_file'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/builder.rb:66:in `parse_file'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:349:in `build_app_and_options_from_config'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:249:in `app'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:422:in `wrapped_app'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:312:in `block in start'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:379:in `handle_profiling'
app_1           |   from /usr/local/bundle/gems/rack-2.2.2/lib/rack/server.rb:311:in `start'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/commands/server/server_command.rb:39:in `start'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/commands/server/server_command.rb:147:in `block in perform'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/commands/server/server_command.rb:138:in `tap'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/commands/server/server_command.rb:138:in `perform'
app_1           |   from /usr/local/bundle/gems/thor-1.0.1/lib/thor/command.rb:27:in `run'
app_1           |   from /usr/local/bundle/gems/thor-1.0.1/lib/thor/invocation.rb:127:in `invoke_command'
app_1           |   from /usr/local/bundle/gems/thor-1.0.1/lib/thor.rb:392:in `dispatch'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/command/base.rb:69:in `perform'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/command.rb:46:in `invoke'
app_1           |   from /usr/local/bundle/gems/railties-6.0.2.1/lib/rails/commands.rb:18:in `<main>'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `require'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:23:in `block in require_with_bootsnap_lfi'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require_with_bootsnap_lfi'
app_1           |   from /usr/local/bundle/gems/bootsnap-1.4.6/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:31:in `require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `block in require'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:291:in `load_dependency'
app_1           |   from /usr/local/bundle/gems/activesupport-6.0.2.1/lib/active_support/dependencies.rb:325:in `require'
app_1           |   from bin/rails:4:in `<main>'

I've verified that the gem exception_notification is indeed installed by running docker exec -it <container-name> gem list, which includes exception_notification (4.4.3) in the output, and also running docker exec -it <container-name> gem which exception_notification which gives /usr/local/bundle/gems/exception_notification-4.4.3/lib/exception_notification.rb

Running Ruby on Rails v6.0.2 and Ruby v2.6.3

Original Q&A

There are 2 best solutions below

**Kaom Te** · Answer 1

I had some similar problems when using Rails and Docker. Bootsnap cache may be stale.

Try removing the cache

rm tmp/cache/bootsnap-load-path-cache

You might also try restarting Spring

spring stop

It should restart automatically.

**Anand Bait** · Answer 2

Anand Bait On 15 August 2020 at 20:10

Try require 'exception_notification/rails'

cannot load such file -- exception_notification (LoadError)

There are 2 best solutions below

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