Rails 5.1: “unknown firstpos: NilClass” - Issue reloading application
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Rails 5.1: “unknown firstpos: NilClass” - Issue reloading application
Following an upgrade from Rails 5.0 to 5.1 I'm getting this error anytime the app reloads, either from code changes during rails server or if I call reload! from the console.
rails server
reload!
🌶 13:53$ rc
Loading development environment (Rails 5.1.1)
2.3.1 :001 > reload!
Reloading...
ArgumentError: unknown firstpos: NilClass
from (irb):1
2.3.1 :002 >
https://github.com/rails/rails/blob/master/actionpack/lib/action_dispatch/journey/gtg/builder.rb
Application Trace is empty, here's the Framework Trace:
actionpack (5.1.1) lib/action_dispatch/journey/gtg/builder.rb:99:in `firstpos'
actionpack (5.1.1) lib/action_dispatch/journey/gtg/builder.rb:22:in `transition_table'
actionpack (5.1.1) lib/action_dispatch/journey/routes.rb:58:in `simulator'
actionpack (5.1.1) lib/action_dispatch/journey/router.rb:92:in `simulator'
actionpack (5.1.1) lib/action_dispatch/journey/router.rb:28:in `eager_load!'
actionpack (5.1.1) lib/action_dispatch/routing/route_set.rb:382:in `eager_load!'
railties (5.1.1) lib/rails/application/routes_reloader.rb:26:in `each'
railties (5.1.1) lib/rails/application/routes_reloader.rb:26:in `execute'
railties (5.1.1) lib/rails/application/finisher.rb:141:in `block (2 levels) in <module:Finisher>'
activesupport (5.1.1) lib/active_support/callbacks.rb:413:in `instance_exec'
activesupport (5.1.1) lib/active_support/callbacks.rb:413:in `block in make_lambda'
activesupport (5.1.1) lib/active_support/callbacks.rb:197:in `block (2 levels) in halting'
activesupport (5.1.1) lib/active_support/callbacks.rb:601:in `block (2 levels) in default_terminator'
activesupport (5.1.1) lib/active_support/callbacks.rb:600:in `catch'
activesupport (5.1.1) lib/active_support/callbacks.rb:600:in `block in default_terminator'
activesupport (5.1.1) lib/active_support/callbacks.rb:198:in `block in halting'
activesupport (5.1.1) lib/active_support/callbacks.rb:507:in `block in invoke_before'
activesupport (5.1.1) lib/active_support/callbacks.rb:507:in `each'
activesupport (5.1.1) lib/active_support/callbacks.rb:507:in `invoke_before'
activesupport (5.1.1) lib/active_support/callbacks.rb:130:in `run_callbacks'
activesupport (5.1.1) lib/active_support/execution_wrapper.rb:108:in `run!'
activesupport (5.1.1) lib/active_support/reloader.rb:113:in `run!'
activesupport (5.1.1) lib/active_support/execution_wrapper.rb:70:in `block in run!'
activesupport (5.1.1) lib/active_support/execution_wrapper.rb:67:in `tap'
activesupport (5.1.1) lib/active_support/execution_wrapper.rb:67:in `run!'
activesupport (5.1.1) lib/active_support/reloader.rb:59:in `run!'
actionpack (5.1.1) lib/action_dispatch/middleware/executor.rb:10:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/debug_exceptions.rb:59:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/show_exceptions.rb:31:in `call'
railties (5.1.1) lib/rails/rack/logger.rb:36:in `call_app'
railties (5.1.1) lib/rails/rack/logger.rb:24:in `block in call'
activesupport (5.1.1) lib/active_support/tagged_logging.rb:69:in `block in tagged'
activesupport (5.1.1) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (5.1.1) lib/active_support/tagged_logging.rb:69:in `tagged'
railties (5.1.1) lib/rails/rack/logger.rb:24:in `call'
sprockets-rails (3.2.0) lib/sprockets/rails/quiet_assets.rb:13:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/remote_ip.rb:79:in `call'
request_store (1.3.2) lib/request_store/middleware.rb:9:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/request_id.rb:25:in `call'
rack (2.0.3) lib/rack/method_override.rb:22:in `call'
rack (2.0.3) lib/rack/runtime.rb:22:in `call'
activesupport (5.1.1) lib/active_support/cache/strategy/local_cache_middleware.rb:27:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/executor.rb:12:in `call'
actionpack (5.1.1) lib/action_dispatch/middleware/static.rb:125:in `call'
rack (2.0.3) lib/rack/sendfile.rb:111:in `call'
railties (5.1.1) lib/rails/engine.rb:522:in `call'
puma (3.9.1) lib/puma/configuration.rb:224:in `call'
puma (3.9.1) lib/puma/server.rb:602:in `handle_request'
puma (3.9.1) lib/puma/server.rb:435:in `process_client'
puma (3.9.1) lib/puma/server.rb:299:in `block in run'
puma (3.9.1) lib/puma/thread_pool.rb:120:in `block in spawn_thread'
5 Answers
5
I just faced exactly the same problem. I sovled it by setting:
config/environments/development.rb
from:
# Do not eager load code on boot.
config.eager_load = true
to:
**# Do not eager load code on boot.
config.eager_load = false
Hope this helps!
Cheers, Nic.
I prefer to use eager_load on dev boot as a sort of static code analyzer. If you have a syntax error anywhere you know about it immediately. That said, I tried it anyway and unfortunately it didn't have any effect. I also tried building a new rails 5.1.1 app and both ways worked as expected, with and without spring... humm
– JP Duffy
Jun 14 '17 at 14:24
worked for me, but there still must be another way to do it (or why would there be this option anyway from 5.1 on)
– Maxim Zubarev
Jul 2 '17 at 14:35
It seems very undesirable to disable a key feature of Rails just to get around this problem, let alone a feature that may be necessary for some.
– Todd
Sep 11 '17 at 23:27
Seems it is Spring hanging or something. Just run spring stop and it should go away. Alternatively you can start the rails console without spring like this:
spring stop
DISABLE_SPRING=true rails c.
DISABLE_SPRING=true rails c
I don't run Spring, we ran into problems with it when it was introduced and never bothered with it since. For now I've just postponed my 5.1 upgrade. 5.0 is working great.
– JP Duffy
Jul 10 '17 at 14:44
Doesn't help for me
– Evmorov
Aug 22 '17 at 13:05
Workaround found! https://github.com/rails/rails/pull/32296
The pull request is not merged, and will probably only be in 5.2+ anyway. Adding a monkey patch with the one-line change fixed the problem entirely for me.
config/initializers/routes.rb
# MONKEY PATCH!!!
# https://github.com/rails/rails/pull/32296
#
# Fixes:
# * Development mode deadlocks
# * ArgumentError: unknown firstpos: NilClass
#
# Allows use of "config.eager_load = true"
module ActionDispatch
module Journey
class Routes
def simulator
@simulator ||= begin
gtg = GTG::Builder.new(ast).transition_table unless ast.blank?
GTG::Simulator.new(gtg)
end
end
end
end
end
For the record: 32296 was closed in favor of github.com/rails/rails/pull/33118 and the bug is confirmed to still exist in 5.2.0
– genkilabs
Jun 20 at 16:45
This was the only thing that worked for me. I wrapped mine with github.com/ingoweiss/gem-patching (old gem, still works)
Gem.patching("rails", "5.2.0") do...end so I won't forget to remove it– Chris Beck
Aug 7 at 20:39
Gem.patching("rails", "5.2.0") do...end
Problem still there with
5.2.1– bragboy
Aug 21 at 17:27
5.2.1
I started having this problem after upgrading Rails from 5.1 to 5.2
It got solved by:
spring stop
spring binstub --all
spring start
rails s
This actually worked for me! No monkey patch needed, thanks man! Will have to see if it lasts but if it does it's great :)
– Martin Vandersteen
Jul 20 at 9:59
This certainly modified my binstubs for
spring, rake, rspec, rails but it didn't make the bug go away– Chris Beck
Aug 7 at 20:23
spring, rake, rspec, rails
You will not get this bug in production environment and in a test environment (if you don't use Spring).
Because this bug "ArgumentError: unknown firstpos: NilClass" you got in "reload" when it tried to reload some your classes.
In production and test environments all things are in cache, so all your things will be cached and bug will not happen
Unfortunately (for now) for the development environment, I also found only this solution
config.eager_load = false
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can you try this link collectiveidea.com/blog/archives/2016/07/22/…
– skam
Aug 29 '17 at 11:32