Ran into a long existing bug in SharePoint 2013 where you have a couple of conditions prevent uploading a file to a document library by drag & drop.
The conditions are these:
The document library is exposed as a webpart view on the page.
The page is a published page (as opposed to draft or checked-out) in a site where publishing is enabled at the site collection level. (note that drag and drop uploads work if the page is not published.)
A number of posts describe the problem out on the interwebs, but I couldn’t find a single one with a working solution…
They talked about dragdrop.js and the SP.Utilities.CommandBlock undefined error, and setting x-ua-compatible to IE9, and a few other pieces to the puzzle…
After a consult with the gang around the BlueMetal office, we collectively arrived at the following solution, using Script On Demand functionality…
The fix is to add the following to a script block at the bottom of the master page associated with the published page:
//Drag & Drop fix for publishing pages
That forces those libraries to load for your masterpage even if nothing else on the page requires them.