Hiki Error

invalid byte sequence in UTF-8 (ArgumentError)
/usr/local/hiki/lib/hiki/util.rb:169:in `split'
/usr/local/hiki/lib/hiki/util.rb:169:in `unified_diff'
/usr/local/hiki/lib/hiki/command.rb:377:in `rescue in cmd_diff'
/usr/local/hiki/lib/hiki/command.rb:372:in `cmd_diff'
/usr/local/hiki/lib/hiki/command.rb:131:in `block in dispatch'
/usr/lib/ruby/2.7.0/timeout.rb:95:in `block in timeout'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `block in catch'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `catch'
/usr/lib/ruby/2.7.0/timeout.rb:33:in `catch'
/usr/lib/ruby/2.7.0/timeout.rb:110:in `timeout'
/usr/local/hiki/lib/hiki/command.rb:104:in `dispatch'
/usr/local/hiki/hiki.cgi:36:in `block in <top (required)>'
/usr/local/hiki/lib/hiki/storage/base.rb:13:in `open_db'
/usr/local/hiki/hiki.cgi:34:in `<top (required)>'
/home/itpass/public_html/hiki/hiki.cgi:2:in `load'
/home/itpass/public_html/hiki/hiki.cgi:2:in `<main>'