I think this might be a Mac OS X only bug. Mac OS X stores filenames case sensitively but compares filenames without case sensitivity. same file: script/../config/../public/document/thumbnail/tmp/1137259310.479525.806/barcelona.JPG and script/../config/../public/document/thumbnail/tmp/1137259310.479525.806/barcelona.jpg /usr/lib/ruby/1.8/fileutils.rb:846:in `fu_each_src_dest'' /usr/lib/ruby/1.8/fileutils.rb:845:in `fu_each_src_dest0'' /usr/lib/ruby/1.8/fileutils.rb:845:in `fu_each_src_dest'' /usr/lib/ruby/1.8/fileutils.rb:572:in `mv'' ./script/../config/../vendor/plugins/file_column/lib/file_column.rb:247:in `store_upload'' -- Posted via http://www.ruby-forum.com/.