one way is to try with the default twenty fourteen theme. and then seeing if the problem persists.
Still nothing changed
I installed the twenty fourteen theme
and tried again but same same the add media is not working
Ok, one last idea. It’s a long shot, but I’m completely out of other ideas myself, sorry. 🙁
Try adding define('CONCATENATE_SCRIPTS', false); to your wp-config.php file just below the define('DB_HOST' line.
http://codex.wordpress.org/Editing_wp-config.php#Disable_Javascript_Concatenation
I am having the same problems with add media. I get the error message when adding new files. I’ve tried everything on this list and got no results. I have tried it on google chrome and just updated explorer. Still nothing.
That’s a completely different issue. You get an error message when you add files, but the original poster here can’t even click the button to add files.
Please open a separate thread for your issue: http://wordpress.org/support/forum/how-to-and-troubleshooting#postform
