I saw that result code during khttpd development/testing, and eventually concluded that it must be due to the browser giving up on a refresh attempt, closing the connection, and then retrying the refresh.

This will happen whenever the player does not respond to the player before the player asks for the NEXT refresh, which can happen if the player is busy with disk access.

To test this theory, do a full-collection shuffle/unshuffle while running the browser thingie.. should see lots of those messages.

Cheers