Here is what you need to do to fix this simply take you ht access file put it on your desktop and open with notepad. Make sure sef in joomla is on and you htaccess is .htaccess then scroll to the bottom of the .htaccess in notpad and add these lines the reupload ang it will say finished uploading instead of canoul not communicate with server. Please let me know if this works for other becuase it is a nice gallery.

add this

SecFilterEngine Off

SecFilterScanPOST Off