Front panel went away

[Digharatta]

Describe the bug
Unexpectedly, when I was away, my Decidim front Panel went to Bahamas, and left a message: "500 Internal Server Error". However, Admin and System Panel still work.
In the Nginx error log, there's: "Error during failsafe response: wrong number of arguments", and later "errors_controller.rb:10:in `internal_server_error'" Mysteriously, when I restore a Digital Ocean backup (of the version which worked very well), the error persists.
Perhaps there's a known way to invite the front panel back?

I'm willing to reinstall Decidim, if there's no better way. How can I preserve the database?

Screenshots
Here's a part of Nginx error log:

App 1131 output:   /usr/lib/ruby/vendor_ruby/phusion_passenger/utils.rb:113:in `block in create_thread_and_abort_on_exception'
App 1131 output: Error during failsafe response: wrong number of arguments (given 3, expected 2)
...
App 1131 output:   /home/decidim/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/actionpack-5.2.1/lib/action_controller/metal/instrumentation.rb:45:in `render'
App 1131 output:   /home/decidim/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/decidim-core-0.13.0/app/controllers/decidim/errors_controller.rb:10:in `internal_server_error'

[mrcasals]

This seems to be an error on phusion_passenger gem 😕 Can you check the repo for that gem in case someone else is having the same problem?

[Digharatta]

@mrcasals Hey, it turned out that I (after upgrade attempt?) have got two passengers with three problems each:

decidim@ubuntu-s-1vcpu-1gb-fra1-01:~$ gem check passenger
Checking gems...

passenger-5.3.3.gem has 3 problems
  download_cache/agent-x86_64-linux.tar.gz:
    Extra file
  download_cache/nginx-1.14.0-x86_64-linux.tar.gz:
    Extra file
  src/helper-scripts/download_binaries/Makefile:
    Extra file

passenger-5.3.4.gem has 3 problems
  download_cache/agent-x86_64-linux.tar.gz:
    Extra file
  download_cache/nginx-1.14.0-x86_64-linux.tar.gz:
    Extra file
  src/helper-scripts/download_binaries/Makefile:
    Extra file

No wonder front panel went to Bahamas.
@microstudi mentioned that:

If the output complains about having 2 copies of passenger installed, then passenger may be using the wrong copy of it.

https://github.com/Platoniq/decidim-install/blob/master/decidim-bionic.md

[Digharatta]

After good old

sudo apt update
sudo apt upgrade

Admin panel also went to Bahamas, and now I read:
Web application could not be started by the Phusion Passenger application server.

App 32199 output:     /usr/share/passenger/helper-scripts/rack-preloader.rb:188:in `<module:App>'
App 32199 output:     /usr/share/passenger/helper-scripts/rack-preloader.rb:30:in `<module:PhusionPassenger>'
App 32199 output:     /usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `<main>'
[ E 2018-08-13 17:43:10.5842 31981/Tg age/Cor/App/Implementation.cpp:221 ]: Could not spawn process for application /home/decidim/decidim-app: The application encountered the following error: Could not find nokogiri-1.8.4 in any of the sources (Bundler::GemNotFound)
  Error ID: 054d46ff
  Error details saved to: /tmp/passenger-error-qOPL87.html

[Digharatta]

After

gem update --system
gem install nokogiri
bundle install

Admin panel returned back, the status quo is restored, and now I again see the good old 500 error.

[Digharatta]

Now I've reinstalled Passenger, and only one version, 5.3.3, remains (besides the version installed through APT repository).

Log features good old "failsafe" error.

[Digharatta]

Seems like there has been a conflict between two instances of Passenger. I re-installed Decidim with just one Passenger, from Apt repository, and so far everything works fine:
Platoniq/decidim-install#15

[oriolgual]

Closing this since it doesn't seem to be a Decidim bug.