Django Broken pipe in Debug mode

Solution 1:

This isn't really an issue with your site, more with the Django devserver: see this Django ticket. To put it bluntly, just ignore it as it is a known error, and won't be fixed.

In that ticket's comments a quite clear explanation is given:

According to many sources the 'Broken Pipe' is a normal browser quirk. For example, the browser reads from the socket and then decides that the image it's been reading apparently didn't change. The browser now this (forcefully) closes the connection because it does not need more data. The other end of this socket (the python runserver) now raises a socket exception telling the program that the client 'Broke the socket pipe'.

Solution 2:

Nginx directive proxy_intercept_errors off; (disabled by default) is what I needed