This is a known bug.
From https://bugs.php.net/bug.php?id=60471:
[2011-12-08 15:01 UTC] lolautruche at gmail dot com Description:
------------
From time to time, built-in server with router script logs this kind of stuff :
[Thu Dec 8 13:39:29 2011] 127.0.0.1:50358 Invalid request (Unexpected
EOF)
This happens quite randomly, whatever the script has a close tag or
not, whatever it has a blank line after close tag or not.
And the explanation:
[2012-02-23 18:45 UTC] michal dot pipa dot xsolve at gmail dot com
...
Chromium has feature called "Predict network actions to improve page
load performance" and its enabled by default. It works this way, that
if HTML page has links to some resources, than Chromium opens about
10 TCP connections in advance. And then if browser has less than 10
resources to fetch, unused connections times out after 10 seconds.
And this (empty payload) causes PHP server to display "Invalid request
(unexpected EOF)" message.
It is a harmless error from the PHP built-in server.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…