Hey @kaluznyo, what version of MIssion Control are you using?

Sorry ! 1.0.1, and rails 8.0.1

Huh, 1.0.1 should have a fix for that problem... could you copy the full trace from the error?

The error and the trace is on my 'main' app, when it crash, mission control is still alive

https://gist.github.com/kaluznyo/e99d274c971c4a37e534e43aa2573535

Oh, interesting... it's different from the error I fixed in version 1.0.1. 🤔 The code here is only used in Mission Control's controllers, so it shouldn't affect the code path in your error trace 🤔

Could you check what locale is being passed to the translate call in /PROJECT_ROOT/app/views/tasks/index.html.erb:17?

I just use the translate (t()) rails method on line 17. I suppose it's related to this, because when I put in production with Mission Control tab open, my main app crash. If I put in production without Mission Control open, it's work. My intuition, says the available locals is redefined globally by Mission Control. But if you say it's not possible, I'm probably wrong !

I put in production with Mission Control tab open, my main app crash. If I put in production without Mission Control open, it's work.

Huh, so do you mean that in both cases, Mission Control is installed in your app, just that in the second case you're not using it? So strange!

Ok, I reproduce in local, start my server, without any tab open on my localhost, got to /jobs (url for mission control), and then go to my main page where I have I18n. Crash

@kaluznyo, could I get more details on how you have configured Mission Control? The routes where it's mounted and all that?

Only
mount MissionControl::Jobs::Engine, at: "/jobs"

This is so strange. The custom I18n configuration is only used here, to set I18n.config, which is thread-safe, so it shouldn't affect a subsequent request at all.

Could you debug your app so that you check the value of I18n.available_locales first on the beginning of a request to / after restarting your server, then on a request to /jobs and then on another request to /?

I try to make a new rails 8 project on https://github.com/kaluznyo/test_mc_i18n, the only modification is :

• Add a dummy controller with a show method. It use <%= t('.test') %>
• Add a fr.yml and config.i18n.default_locale = :fr on application.rb
• Add Mission Control

I reproduce with the same way. Launche server, open directly /jobs, then /dummy -> Crash. Inverse work well.

Yes I agree with you... I don't know where is wrong, the I18n.available_locales seems good on console on crashed page...

Oh, thank you so much for that reproduction app! I can reproduce with that, so I should be able to debug it. Looking into it...

To add more incomprehension, if I add p I18n.locale_available?(:fr) in the gem on app/controllers/mission_control/application_controller.rb, line 24 at the beginning on set_current_locale(&block)... I think it's work .....

@kaluznyo I think I found the problem thanks to your app and reproduction steps. The key is that the request to /jobs needs to happen before any other request 😅 The problem is that available_locales defined in Mission Control's I18n configuration ends up polluting the non-thread safe class variable @@available_locales_set 😅 To make things a bit more confusing, there's yet a 3rd config class being used here, Action View's own I18n config proxy class, that I didn't know.

I have a possible fix ready, will push it tomorrow!

@kaluznyo, I've prepared a fix in #231, could you confirm whether it fixes the bug for you?

Works fine ! Thanks !