I got an issue on backend, */catalog_product/edit after applying successfully the patch SUPEE-8788.
The error "Uncaught ReferenceError: Uploader is not defined" is returned.
The uploader buttons are displayed but don't work (because of this JS error I guess).
Is someone got the same error? If yes, how did you fixed it?
EDIT: This initial issue is now fixed.
No js merge is disabled (I'm working locally).
But I've found the problem. The cause was: me ':)
I ran the PATCH on my distant server, then retrieve all the updated ressources locally.
I've just forgot to take the folder /js/mage/adminhtml/uploader
So now the uploader is opening the windows for file selecting.
BUT, when I click on "upload files", the uploader seems working fine, "complete" message is displayed.
BUT no image seems really uploaded (the file is not added to the product images list).