GNOME icon loading error in Ubuntu Xenial 16.04

My newly installed Ubuntu Xenial 16.04 LTS has some gnome based applications having problem with png images. For example, I got this message when trying to open stadict:

"Can not load image. Couldn't recognize the image file format for file '/usr/share/pixmaps/stardict.png'"

The only relevant info I found is from http://gentoo.2317880.n4.nabble.com/Icon-loading-problem-after-updating-for-GNOME-based-application-td146755.html

but the solution there is not working for me -- I got

Directory '/usr/share/mime-info/packages' does not exist!

and

Directory '/home/me/.config/mime/packages' does not exist!

for the first and third command, and the second command didn't help solving the problem.

I've been using stadict for ages, and Ubuntu Xenial 16.04 is the first time that I'm having such problem. The file is perfectly fine viewing by any other apps.