diff --git a/app/libs/util.rb b/app/libs/util.rb
index 7839b2304..6c7784606 100644
--- a/app/libs/util.rb
+++ b/app/libs/util.rb
@@ -39,6 +39,7 @@ module Util
   end
 
   def extract_content(str)
+    return '' if str.blank?
     str.gsub(/<\/?.*?>/, '').gsub(/[\n\t\r]/, '').gsub(/&nbsp;/, '')
   end
 end
\ No newline at end of file