Error

invalid byte sequence in US-ASCII
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:804:in `strip'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:804:in `render_preface'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:832:in `render_sub_page'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:288:in `block in render_page'
/usr/lib/ruby/3.2.0/cgi/core.rb:370:in `out'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:282:in `render_page'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:70:in `run'
/var/www/html/pictures/2014/group_quebec/sub_day_10/index.rb:1011:in `<main>'