# Strange repeated errors **URL:** \ **Category:** NGINX\ **Created:** [May 22, 2012, 3:39pm UTC](https://www.ruby-forum.com/t/strange-repeated-errors/219940 "2012-05-22T15:39:08Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [May 22, 2012, 3:39pm UTC](https://www.ruby-forum.com/t/strange-repeated-errors/219940/1 "2012-05-22T15:39:08Z")
Hi, I’ve a tail -f error.log running, and saw some strange errors, repeated each minutes at same second (26), from same host and same URL : 2012/05/22 15:13:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.26:80/?track=lang-BR&uid=159669961](http://10.0.0.26:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:14:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.26:80/?track=lang-BR&uid=159669961](http://10.0.1.26:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:15:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.31:80/?track=lang-BR&uid=159669961](http://10.0.0.31:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:16:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.31:80/?track=lang-BR&uid=159669961](http://10.0.1.31:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:17:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.32:80/?track=lang-BR&uid=159669961](http://10.0.0.32:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:18:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.32:80/?track=lang-BR&uid=159669961](http://10.0.1.32:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:19:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.33:80/?track=lang-BR&uid=159669961](http://10.0.0.33:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:20:26 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.33:80/?track=lang-BR&uid=159669961](http://10.0.1.33:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:21:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.34:80/?track=lang-BR&uid=159669961](http://10.0.0.34:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:22:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.34:80/?track=lang-BR&uid=159669961](http://10.0.1.34:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:23:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.28:80/?track=lang-BR&uid=159669961](http://10.0.0.28:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:24:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.28:80/?track=lang-BR&uid=159669961](http://10.0.1.28:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:25:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.0.25:80/?track=lang-BR&uid=159669961](http://10.0.0.25:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” 2012/05/22 15:26:27 [error] 12410#0: \*4714521 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: “[http://10.0.1.25:80/?track=lang-BR&uid=159669961](http://10.0.1.25:80/?track=lang-BR&uid=159669961)”, host: “[sub.mydomain1.com](http://sub.mydomain1.com)” I’ve curl this URL, then ab (ApacheBench) it, and wasn’t able to reproduce this error. Did you have an idea how to debug that ? ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [May 22, 2012, 6:22pm UTC](https://www.ruby-forum.com/t/strange-repeated-errors/219940/2 "2012-05-22T18:22:26Z")
Hello! On Tue, May 22, 2012 at 03:37:54PM +0200, Greg wrote: > “[http://10.0.0.26:80/?track=lang-BR&uid=159669961](http://10.0.0.26:80/?track=lang-BR&uid=159669961)”, host: > request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: > upstream, client: 177.65.240.189, server: [www.mydomain1.com](http://www.mydomain1.com), > (110: Connection timed out) while reading response header from > 2012/05/22 15:21:27 [error] 12410#0: \*4714521 upstream timed out > “[sub.mydomain1.com](http://sub.mydomain1.com)” > “[http://10.0.1.28:80/?track=lang-BR&uid=159669961](http://10.0.1.28:80/?track=lang-BR&uid=159669961)”, host: > request: “GET /?track=lang-BR&uid=159669961 HTTP/1.1”, upstream: > “[http://10.0.1.25:80/?track=lang-BR&uid=159669961](http://10.0.1.25:80/?track=lang-BR&uid=159669961)”, host: > “[sub.mydomain1.com](http://sub.mydomain1.com)” > > I’ve curl this URL, then ab (ApacheBench) it, and wasn’t able to > reproduce this error. Did you have an idea how to debug that ? Looks like your upstream servers fail to respond in time for some reason and nginx tries upstream servers configured as per proxy\_next\_upstream (see [Module ngx\_http\_proxy\_module](http://nginx.org/r/proxy_next_upstream)). The reason why your backends time out is probably related to a particular request properties, likely something user/cookie related as you can’t reproduce it with just url. Try looking into backend logs. Maxim D. ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [May 23, 2012, 9:18am UTC](https://www.ruby-forum.com/t/strange-repeated-errors/219940/3 "2012-05-23T09:18:01Z")
Hi, Le 22/05/2012 18:21, Maxim D. a crit : > Looks like your upstream servers fail to respond in time for some > reason and nginx tries upstream servers configured as per > proxy\_next\_upstream (see [Module ngx\_http\_proxy\_module](http://nginx.org/r/proxy_next_upstream)). > > The reason why your backends time out is probably related to a > particular request properties, likely something user/cookie > related as you can’t reproduce it with just url. Try looking into > backend logs. You’re right ! But is that normal that next upstreams are tried infinitely ? How many tries did NginX before considere that the request is really failed ? ---
**Author:** ![greg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/71c47a/32.png) [@greg](https://www.ruby-forum.com/u/greg)\ **Post date:** [May 23, 2012, 10:41am UTC](https://www.ruby-forum.com/t/strange-repeated-errors/219940/4 "2012-05-23T10:41:58Z")
Hello! On Wed, May 23, 2012 at 09:17:11AM +0200, Greg wrote: > > backend logs. > > You’re right ! > But is that normal that next upstreams are tried infinitely ? How > many tries did NginX before considere that the request is really > failed ? Normally nginx will try all servers specified in an upstream{} block before giving up. Before 1.3.0 there were infinite loop over upstream servers possible if there were “backup” servers specified in an upstream block. It normally affected only setups with “proxy\_next\_upstream http\_404” used as well, but might also affect normal setups if only specific requests fail and iteration of the loop over backends takes more than fail\_timeout. Maxim D.