t("website_title") nil after moving from Heroku Bamboo to Cedar

Question

I just moved my working Heroku app from Bamboo to Cedar, and now it crashes with:

Rendered devise/sessions/new.html.erb within layouts/application (4.6ms)
ActionView::Template::Error (no implicit conversion of nil into String):
8:          <%= t("website_title") %>

As you can see, t("website_title") seems to be nil, despite the fact that website_title is still in config/locales/en.yml as usual:

en:
  website_title: Cats (All about cats)

Is it a known issue when moving from Bamboo to Cedar?
Any idea how to solve it?

Answer 1

Actually, heroku logs was showing log lines in non-chronological order, which lead me to think the problem was line 8, but in fact it was this problem:

https://github.com/rails/rails/issues/9619

Which I solved as explained by dvdplm there.