Comment 4 for bug 1605189

This is an annoying bug that hasn't been addressed in the two and a half years it has plagued Ubuntu with the Xfce desktop. One can find bug reports going back to 14.04 after a faulty patch broke suspend. Fortunately for the terminally-skilled among us, the workaround is here:

http://askubuntu.com/questions/543921/authentication-required-before-suspend