I saw some people had some issued with the error message "Unable to locate WordPress Content directory (wp-content)" when they are trying to update their plugins. After a number of hours of tracing out the error, I think I found the answer.
What ended up being the problem, at least in my case, was that my FTP root directory did not include my wordpress directory in it. Here is how the plugin update works:
First it goes out an does a search of all the folders in the FTP Root directory to see if it can find your wp-content folder. It literally traverses all the folders it see and sub folders until it can find what it's looking for. In my case, my webserver was not located in the FTP Root folder so it was never finding it. The fix was to change my FTP Root directory to one that includes the wordpress installation folder.
Let me know if that works.
Change your FTP Root directory to one that includes your wordpress install.