Changes with nginx 1.9.15                                        19 Apr
2016
*) Bugfix: "recv() failed" errors might occur when using HHVM as a
   FastCGI server.
*) Bugfix: when using HTTP/2 and the "limit_req" or "auth_request"
   directives a timeout or a "client violated flow control" error 
might
occur while reading client request body; the bug had appeared in
1.9.14.
*) Workaround: a response might not be shown by some browsers if 
HTTP/2
was used and client request body was not fully read; the bug had
appeared in 1.9.14.
*) Bugfix: connections might hang when using the "aio threads"
   directive.
   Thanks to Mindaugas Rasiukevicius.
–
Maxim D.
http://nginx.org/