I very recently launched shadowsinthegrass.com, a crowd-funding website for a short film I am working on. As a donator, you are able to upload an avatar to be presented with your credit. I had limited the file size to 2MB... or so I had thought.

Underneath, the site is built with Flask, served with Gunicorn, and behind an Nginx reverse proxy.

Unfortunately, I received reports that some uploads were failing and reported as "Error: undefined" to the user. Strangely, it didn't seem to be an error in the Python app, as I was not receiving any tracebacks when this error occurred.

It turns out that Nginx has some default configuration that I wasn't expecting.

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