作りながら学ぶRUBY入門第２版をお持ちの方に質問です。

第２６章の３３８ページからある練習５番が正常に作動しましたか？
私はHTTP500内部サーバーエラー（incompatible character encodings: Windows-31J and UTF-8）が起きるなどの問題が発生しました。
もし、問題なく動作した方がいるならば、動作環境とその時記述したコードを教えてください。

私は「windows10でrubyのバージョンは2.41を使用しています」

ちなみにコマンドプロントに出たエラー内容はこちらになります。

cmd
1[2018-09-26 14:59:33] ERROR Encoding::CompatibilityError: incompatible character encodings: Windows-31J and UTF-8
2        (erb):16:in `concat'
3        (erb):16:in `block (3 levels) in evaluate'
4        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/row.rb:82:in `block in each_with_name'
5        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/row.rb:81:in `each'
6        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/row.rb:81:in `each_with_index'
7        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/row.rb:81:in `each_with_name'
8        (erb):13:in `block (2 levels) in evaluate'
9        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/handles/statement.rb:214:in `fetch'
10        F:/ruby2/Ruby24-x64/lib/ruby/gems/2.4.0/gems/dbi-0.4.5/lib/dbi/handles/statement.rb:240:in `each'
11        (erb):12:in `block in evaluate'
12        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/erb.rb:896:in `eval'
13        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/erb.rb:896:in `result'
14        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/erbhandler.rb:83:in `block in evaluate'
15        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/erbhandler.rb:80:in `module_eval'
16        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/erbhandler.rb:80:in `evaluate'
17        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/erbhandler.rb:57:in `do_GET'
18        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/abstract.rb:107:in `service'
19        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/filehandler.rb:307:in `exec_handler'
20        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/filehandler.rb:238:in `do_GET'
21        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/abstract.rb:107:in `service'
22        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpservlet/filehandler.rb:234:in `service'
23        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpserver.rb:140:in `service'
24        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/httpserver.rb:96:in `run'
25        F:/ruby2/Ruby24-x64/lib/ruby/2.4.0/webrick/server.rb:308:in `block in start_thread'
26::1 - - [26/Sep/2018:14:59:33 東京 (標準時)] "GET /ex2605.erb HTTP/1.1" 500 335