Heroku rails app runs locally but gives application error code H10 when opened

Question

I have a Rails app that runs successfully locally and that I've successfully pushed up to my heroku remote. However, when I open the URL I get an application error. If I look at my heroku logs this is what I see:

2020-04-04T23:52:16.920545+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=srseats.herokuapp.com request_id=f9130218-18f9-43b4-9fe7-0b04a0ed5555 fwd="107.137.41.186" dyno= connect= service= status=503 bytes= protocol=http
2020-04-04T23:52:17.490055+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=srseats.herokuapp.com request_id=9928310f-cc3e-4161-89eb-3db5cd527650 fwd="107.137.41.186" dyno= connect= service= status=503 bytes= protocol=http
2020-04-04T23:59:13.244533+00:00 heroku[web.1]: State changed from crashed to starting
2020-04-04T23:59:22.120784+00:00 heroku[web.1]: State changed from starting to crashed
2020-04-04T23:59:22.054662+00:00 app[web.1]: (erb):19:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)
2020-04-04T23:59:22.054723+00:00 app[web.1]: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/erb.rb:876:in `eval'
2020-04-04T23:59:22.054724+00:00 app[web.1]: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/erb.rb:876:in `result'
2020-04-04T23:59:22.054728+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activestorage-5.2.3/lib/active_storage/engine.rb:95:in `block (2 levels) in <class:Engine>'
2020-04-04T23:59:22.054734+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:71:in `instance_eval'
2020-04-04T23:59:22.054735+00:00 app[web.1]: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:71:in `block in execute_hook'

If I run heroku run rails console I get the same undefined method `[]' for nil:NilClass error as I do above:

Traceback (most recent call last):
        83: from /app/bin/rails:9:in `<main>'
        82: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
        81: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
        80: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
        79: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        78: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
        77: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        76: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
        75: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
        74: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands.rb:18:in `<top (required)>'
        73: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command.rb:46:in `invoke'
        72: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command/base.rb:65:in `perform'
        71: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
        70: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
        69: from /app/vendor/bundle/ruby/2.5.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
        68: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/commands/console/console_command.rb:95:in `perform'
        67: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command/actions.rb:15:in `require_application_and_environment!'
        66: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/command/actions.rb:28:in `require_environment!'
        65: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/application.rb:337:in `require_environment!'
        64: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
        63: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
        62: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
        61: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        60: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
        59: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        58: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
        57: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
        56: from /app/config/environment.rb:5:in `<top (required)>'
        55: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/application.rb:361:in `initialize!'
        54: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/initializable.rb:60:in `run_initializers'
        53: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:205:in `tsort_each'
        52: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:226:in `tsort_each'
        51: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:347:in `each_strongly_connected_component'
        50: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:347:in `call'
        49: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:347:in `each'
        48: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:349:in `block in each_strongly_connected_component'
        47: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:431:in `each_strongly_connected_component_from'
        46: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
        45: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/tsort.rb:228:in `block in tsort_each'
        44: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/initializable.rb:61:in `block in run_initializers'
        43: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/initializable.rb:32:in `run'
        42: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/initializable.rb:32:in `instance_exec'
        41: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
        40: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/application/finisher.rb:69:in `each'
        39: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:356:in `eager_load!'
        38: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:475:in `eager_load!'
        37: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:475:in `each'
        36: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:477:in `block in eager_load!'
        35: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:477:in `each'
        34: from /app/vendor/bundle/ruby/2.5.0/gems/railties-5.2.3/lib/rails/engine.rb:478:in `block (2 levels) in eager_load!'
        33: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:246:in `require_dependency'
        32: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/active_support.rb:85:in `depend_on'
        31: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:334:in `depend_on'
        30: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/active_support.rb:47:in `require_or_load'
        29: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/active_support.rb:16:in `allow_bootsnap_retry'
        28: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/active_support.rb:48:in `block in require_or_load'
        27: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:356:in `require_or_load'
        26: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:37:in `load_interlock'
        25: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies/interlock.rb:13:in `loading'
        24: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/concurrency/share_lock.rb:151:in `exclusive'
        23: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies/interlock.rb:14:in `block in loading'
        22: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:37:in `block in load_interlock'
        21: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:378:in `block in require_or_load'
        20: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
        19: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
        18: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
        17: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
        16: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
        15: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
        14: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
        13: from /app/vendor/bundle/ruby/2.5.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
        12: from /app/vendor/bundle/ruby/2.5.0/gems/activestorage-5.2.3/app/models/active_storage/blob.rb:16:in `<top (required)>'
        11: from /app/vendor/bundle/ruby/2.5.0/gems/activestorage-5.2.3/app/models/active_storage/blob.rb:235:in `<class:Blob>'
        10: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:51:in `run_load_hooks'
         9: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:51:in `each'
         8: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:52:in `block in run_load_hooks'
         7: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:67:in `execute_hook'
         6: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:62:in `with_execution_control'
         5: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:71:in `block in execute_hook'
         4: from /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.2.3/lib/active_support/lazy_load_hooks.rb:71:in `instance_eval'
         3: from /app/vendor/bundle/ruby/2.5.0/gems/activestorage-5.2.3/lib/active_storage/engine.rb:95:in `block (2 levels) in <class:Engine>'
         2: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/erb.rb:876:in `result'
         1: from /app/vendor/ruby-2.5.1/lib/ruby/2.5.0/erb.rb:876:in `eval'
(erb):19:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)

I have a hunch it's related to using ActiveStorage but I'm not entirely sure but here's my storage.yml

test:
  service: Disk
  root: <%= Rails.root.join("tmp/storage") %>

local:
  service: Disk
  root: <%= Rails.root.join("storage") %>

# Use rails credentials:edit to set the AWS secrets (as aws:access_key_id|secret_access_key)
# amazon:
#   service: S3
#   access_key_id: <%= Rails.application.credentials.dig(:aws, :access_key_id) %>
#   secret_access_key: <%= Rails.application.credentials.dig(:aws, :secret_access_key) %>
#   region: us-east-1
#   bucket: your_own_bucket

amazon_dev:
  service: S3
  access_key_id: <%= Rails.application.credentials.aws[:access_key_id] %>
  secret_access_key: <%= Rails.application.credentials.aws[:secret_access_key] %>
  region: <%= Rails.application.credentials.aws[:region] %>
  bucket: <%= Rails.application.credentials.aws[:dev][:bucket] %>

amazon_prod:
  service: S3
  access_key_id: <%= Rails.application.credentials.aws[:access_key_id] %>
  secret_access_key: <%= Rails.application.credentials.aws[:secret_access_key] %>
  region: <%= Rails.application.credentials.aws[:region] %>
  bucket: <%= Rails.application.credentials.aws[:prod][:bucket] %>

Any hints or help would be greatly appreciated. Thanks.

Answer 1

I just solved possibly the same problem. Turns out, I didn't have a Rails master key set in Heroku. Here's the info that worked for me:

...we'll take a moment to do an absolutely essential step to ensure Active Storage works with Heroku. Heroku will only be able to unencrypt your credentials.yml.enc if we add our master key (which can be found in config/master.key). However, the master key is gitignored for good reason. Do not check this file into git. We can use the heroku command line to secretly add the key to our heroku config.

$ heroku config:set RAILS_MASTER_KEY=<your-master-key-here>

If you do not do this Active Storage won't work on Heroku and will cause a ton of unhelpful errors.