Index: config/boot.rb
===================================================================
--- config/boot.rb	(リビジョン 23435)
+++ config/boot.rb	(作業コピー)
@@ -4,3 +4,8 @@
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 
 require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
+
+# Explicitly load 'logger' to avoid NameError caused by
+# concurrent-ruby 1.3.5.
+# Reference: https://github.com/rails/rails/issues/54272
+require 'logger'