"Data/enGB/wow-update-enGB-18273.MPQ: World of Warcraft can’t make a required change to an archive file. Be sure you have write permission for the World of Warcraft folder or try running the game in administrator mode. For more information, see"
Thanks, it fixed it.
I had the same problem, just right click your mop directory and select properties, and uncheck "Read-only" and make sure its for all subfolders. Then launch it and you should be fine. :)