500 Internal server error

incompatible encoding regexp match (Windows-31J regexp with UTF-8 string)
/home/rails/gems/blogger/app/models/post.rb:109:in `gsub'
/home/rails/gems/blogger/app/models/post.rb:109:in `social_desc'
/home/rails/gems/blogger/app/views/blogger/_social_meta_info.html.erb:1:in `__home_rails_gems_blogger_app_views_blogger__social_meta_info_html_erb__3767517475061179812_45840'
/home/rails/gems/blogger/app/helpers/blogger_helper.rb:259:in `social_meta_tags'
/home/rails/apps/blog/app/views/layouts/application.html.erb:9:in `_app_views_layouts_application_html_erb___374221803052979704_45340'
params: {"id"=>"8-"}