500 Internal Server Error

invalid byte sequence in UTF-8 (ArgumentError)

/usr/local/rbenv/versions/2.1.4/lib/ruby/2.1.0/cgi/util.rb:37:in `gsub'
/usr/local/rbenv/versions/2.1.4/lib/ruby/2.1.0/cgi/util.rb:37:in `escapeHTML'
/usr/local/rbenv/versions/2.1.4/lib/ruby/2.1.0/erb.rb:933:in `html_escape'
(erb):22:in `rescue in eval_rhtml'
/usr/local/rbenv/versions/2.1.4/lib/ruby/2.1.0/erb.rb:850:in `eval'
/usr/local/rbenv/versions/2.1.4/lib/ruby/2.1.0/erb.rb:850:in `result'
/home/tdiary/tdiary/core/lib/tdiary/base.rb:36:in `rescue in eval_rhtml'
/home/tdiary/tdiary/core/lib/tdiary/base.rb:29:in `eval_rhtml'
/home/tdiary/tdiary/core/lib/tdiary/view.rb:247:in `eval_rhtml'
/home/tdiary/tdiary/core/lib/tdiary/dispatcher/index_main.rb:43:in `run'
/home/tdiary/tdiary/core/lib/tdiary/dispatcher/index_main.rb:6:in `run'
/home/tdiary/tdiary/core/lib/tdiary/dispatcher.rb:26:in `dispatch_cgi'
/home/tdiary/users/hikazoh/index.rb:32:in `<main>'