https://github.com/rails/rails/issues/36546#issuecomment-558773961

debug_rails_6_0.rb

ActiveSupport.on_load(:action_controller_base) do
  bc = ActiveSupport::BacktraceCleaner.new
  bc.remove_silencers!
  bc.add_silencer { |line| line.start_with?(RbConfig::CONFIG["rubylibdir"]) }
  bc.add_silencer { |line| line =~ Regexp.union(
    *(
      %w{ bootsnap railties spring activesupport actionpack zeitwerk thor rack }.
      map{|g| /\A#{g} \([\w.]+\) /}
    ),
    /\Abin\/rails/
  )}
  trace = bc.clean(caller)
  puts "Cleaned backtrace:\n\t#{trace.join("\n\t")}\n"
  puts "Most probably the cause is: #{trace.first}"
  puts "If not - uncomment `raise` at #{__FILE__}:#{__LINE__+1}"
  # raise "i can haz full backtrace"
  exit(1)
end