Deleting preferences did not work for me with Safari on my MacPro.
But, I found this article about the same problem on iPads, see http://ipad.about.com/od/iPad_Troub...ant-Add-Bookmarks-In-iPads-Safari-Browser.htm Unchecking Safari iniCloud allows me to save bookmarks again I will say that I had to reboot several times, before the problem went away, but eventually it seems to be working correctly. Fingers crossed.