HTTP3 php-fpm fastcgi_pass 500 problems

Sergey Kandaurov pluknet at
Sat Oct 10 23:03:02 UTC 2020

> On 10 Oct 2020, at 23:09, Ryan Gould <ryanbgould at> wrote:
> hello awesome nginx developers,
> i am having some odd behavior issues when in http3 / quic mode.
> i am using a completely-up-to-date nginx-quic build on a debian 9 box.
> my nginx php-fpm configuration has been solid and unchanging for years and years.
> if i disable http3 / quic, things work great in http2 mode.  if i enable http3 / quic mode, something is causing all php7.3-fpm pages to generate "500 Internal Server Error" pages.  static html pages render perfectly.
> despite adding all the extra log arguments to nginx and to php7.3-fpm (display_errors and the rest) i am only seeing the following in the nginx error log:
> 2020/10/10 21:19:47 [alert] 10614#0: *37 epoll_ctl(1, -1) failed (9: Bad file descriptor), client: X.X.X, server:, request: "GET /php_test_page HTTP/3"

It would be helpful if you'll be able to provide more details,
such as "nginx -V" output, revision of the nginx-quic branch,
debug log messages for a particular request causing 500 error,
and relevant configuration details.  How to obtain debug log:

Sergey Kandaurov

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