Issues with Page Media in Admin (task.addmedia?)

I just noticed that none of my pages which have media in their folder were showing the media at the bottom of the admin edit page. I went in to add them and was met with this error shown on the thumbnail after importing :
Screen Shot ...

The important part seems to be:
The Requested Resource ... locations.json/task.addmedia was not found on this server.

On second look, this could very well just be an issue with running a server through PHP's built-in server.

Yes, that is definitely it.. The lack of support for URL params is the reason why PHP's built-in web server doesn't work with the admin.

Just as a note, if you don't know it already, the Admin since 1.0 does not run any more on the PHP built-in webserver, and raises an error.

Apparently it does in PHP7? I was able to get to the point where I got that error :)

Yes pretty much everything except params.