# Problem with Nginx returning correct content, but with 404

**URL:** <https://www.ruby-forum.com/t/problem-with-nginx-returning-correct-content-but-with-404/202054>\
**Category:** NGINX\
**Created:** [January 20, 2011, 5:24pm UTC](https://www.ruby-forum.com/t/problem-with-nginx-returning-correct-content-but-with-404/202054 "2011-01-20T17:24:57Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**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:** [January 20, 2011, 5:24pm UTC](https://www.ruby-forum.com/t/problem-with-nginx-returning-correct-content-but-with-404/202054/1 "2011-01-20T17:24:57Z")

</div>

Hello,

We have a setup where we have requests coming into a cache server which  
is in front of an app server. The requests hit nginx on the cache  
server, which makes the request to a process running on the cache  
server. That process will return either the requested content (if in the  
cache) or a 404. In the case of a 404, nginx on the cache server should  
then turn around and make the same request to the app server. The app  
server serves the content, and then nginx on the app server should turn  
around and return the response to the client.

The problem we are seeing is that this works fine for requests of the  
form /admin/fan\_pages, but when requesting css or png content (like  
/stylesheets/common.css , or /images/admin/fan\_pages/refresh.png ), it  
is returning the correct content, but with a 404 code. In this case, the  
local process on the cache server is returning a 404, the nginx on the  
cache server is requesting the page from the app server (which returns  
the page with a 200), but then the cache server is turning around and  
serving the correct content to the client with a 404.

Anybody have any ideas on how/why this is happening? I’ll include config  
files and output below. If there’s a simpler or better setup to  
accomplish what we’re trying to do, I’m happy to try that as well.

Thanks,  
–Austin

ngrep output (.185 is the cache server, .165 is the app server):

# 

T 24.227.153.188:54091 → 10.102.38.185:80 [AP]  
GET /stylesheets/common.css HTTP/1.1.  
Host: [test5.involver.com](http://test5.involver.com).  
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US;  
rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8.  
Accept:  
text/html,application/xhtml+xml,application/xml;q=0.9,_/_;q=0.8.  
Accept-Language: en-us,en;q=0.5.  
Accept-Encoding: gzip,deflate.  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,\*;q=0.7.  
Keep-Alive: 115.  
Connection: keep-alive.  
Cookie:  
involver-auth=eyJlbWFpbCI6ImF1c3Rpbi5taWxsc0BpbnZvbHZlci5jb20iLCJzaWduYXR1%0AcmUiOiJLTDA5TmZvMG9QR3V2OUl3QTFkekFWOG1rU04wdkU1d2UyMzBvSjA3%0ATGhvUzJSTDNQOU5tdjRwM09FOFRcblFlUzUvWkFScmxXT29UeldIOVlONTJa%0AUEFzVzdDOXlQdUI1UUZDZURZR3dLZUgzT2RTMVpKbm96ZTY0Q1xuYjk2QUhU%0Aa25FVGdpWmRHaFA4eVJkaE13SDB3YmVkS25MejNGeC9Wd2I4WDhYSDNVM1Yw%0AMkl3RUwwRjNDXG5BS3h3ekFTMlhINHU4b0RXUVM1VkorZ2c4eTFUS2V0UCtw%0AbUVZbXVwN01pcUlXa3BDRnBBSVN2WU5TeXZcbmQ0ekhXWWhDSUE5Ulo4UXY.  
.

#### 

T 10.102.38.185:42920 → 10.102.38.165:80 [AP]  
GET /stylesheets/common.css HTTP/1.0.  
X-Real-IP: 24.227.153.188.  
X-Forwarded-For: 24.227.153.188.  
Host: [test5.involver.com](http://test5.involver.com).  
Connection: close.  
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US;  
rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8.  
Accept:  
text/html,application/xhtml+xml,application/xml;q=0.9,_/_;q=0.8.  
Accept-Language: en-us,en;q=0.5.  
Accept-Encoding: gzip,deflate.  
Accept-Charset: ISO-8859-1,utf-8;q=0.7,\*;q=0.7.  
Cookie:  
involver-auth=eyJlbWFpbCI6ImF1c3Rpbi5taWxsc0BpbnZvbHZlci5jb20iLCJzaWduYXR1%0AcmUiOiJLTDA5TmZvMG9QR3V2OUl3QTFkekFWOG1rU04wdkU1d2UyMzBvSjA3%0ATGhvUzJSTDNQOU5tdjRwM09FOFRcblFlUzUvWkFScmxXT29UeldIOVlONTJa%0AUEFzVzdDOXlQdUI1UUZDZURZR3dLZUgzT2RTMVpKbm96ZTY0Q1xuYjk2QUhU%0Aa25FVGdpWmRHaFA4eVJkaE13SDB3YmVkS25MejNGeC9Wd2I4WDhYSDNVM1Yw%0AMkl3RUwwRjNDXG5BS3h3ekFTMlhINHU4b0RXUVM1VkorZ2c4eTFUS2V0UCtw%0AbUVZbXVwN01pcUlXa3BDRnBBSVN2WU5TeXZcbmQ0ekhXWWhDSUE5Ulo4UXY.  
.

## 

T 10.102.38.165:80 → 10.102.38.185:42920 [A]  
HTTP/1.1 200 OK.  
Server: nginx/0.7.65.  
Date: Thu, 20 Jan 2011 01:14:02 GMT.  
Content-Type: text/css.  
Last-Modified: Wed, 19 Jan 2011 22:20:44 GMT.  
Connection: close.  
Expires: Sun, 17 Jan 2021 01:14:02 GMT.  
Cache-Control: max-age=315360000.  
Content-Encoding: gzip.  
.  
…ZYo.H.~…E#~.n`..iIF..$.......b..@h.-.0E $.c.........{... ............?............}~.~.....`….y…?.._|?Z.N.z.\>…$.=…I…%…U…U…D.:a5_…~.nE…e…V…V.L…rs…YQ…d6…D.Z…Z…D.E…y…  
…)e…7…][yD.tV](http://yD.tV)[^…1\*J.=?#6{q&`.d.G..s...^_...2+x]-2..q.~...t.K.....4!.vbQ.u&`.1I.;.%…/…E…0I.m…o…4…]u…!..+…\<{…$.Ws6.Av.Q\<…UE.&…J)M..?y7._…#k.m].@…H.:.P.G.j…X\_Q…+.v+…10Z…-.y…xy}./…+…Eo.-.\<…Q…P….…&…  
…“…$.9\<.I.O.H?..?.)…Ed…Ncp…].U.E…47…:.t…r~…x…i…X…h…E.]…d…gh3uLo:…](…(”.c.1…:y.=T…i’…3iW.E.Q(.XB…PC…o.W…b…t…[…6\Q.io…H…D…Q…/…M  
.5k.p@S.}.o\<…[.h!k.$.Q4.‘…wiR.I…C…2…Z…L…a…Fs…B…hHo8…c.d…HxK9…’{…%}…h…e.z.\>…?._…^.,(.c  
…X2…t…P.Q.s)…N]…$.1.?..@…,s…Z…1X…M…pF…d.,…a…y…l.P…R.‘(h.  
…Ek…N…G…O$…#…k…L.t…4=…E^1r.&…SK)…[].X…_j(.U…V.V1H…gQ…u.Nk…m.7&…L.M…|K.H…,8…I8…J…y.F…0…T.4.  
x.,!..b.O…&…q.9.f.u…E…\<…8…8.A…B&@.&…/…]…OX.~.+nR.z,n…_…{  
…{S…]L…`.......LoG..[3..3.W|.f...t]......}/..X..5.P...Q.w.b.P..Ix.e(.h.T.0.......y.....l[..J...a2..>.R.{%e .,removed_email_address@domain.invalid....[..5.../p...;..Uu.....Y....t4.D._.K..'.U....R.z.*..+...Kp.....L"......"...tb...0.uB..p$+.@D5.{..+Uk..*....M.?[4..D....S.^~x..a ..J.F+.i'...=L2._.........X...._.....2..]..k...o(.lp....\....\)...*....T.......L.O..z...Z9.......RP/I.&......(...q.7[.Pb!..7.>...<./..'.P....c"...A..c .sf8..........d.MA.;`…H…6.ut2K…@…g7…P…6.3p…Z…"…l…}V60.x.y.#…)y.P…X…C}.t…9…7…b…)9.T…m…^7.%…2!~L…1R…%…:uBt.3…@…B…&.d…r:…`.A..'..B.y.......|........F...b....n.@.../.y.O.$v.)....u*B..P......f..x8nD.6...T..z.L.{.j...|..#...b......M.u...|)td........G...B.$.wp>6@q6.8.0.P&j..].l.w..A....+....%N......h....@.x.C.%i.....:Y].._.l......./,..Q..Lj....|+)...........7.-R.....(..].C......D$..pq.c@.K.......... ..2..k....$e.P.... .v..r....U.sx...]...$$$ .4.&.........G.....-...o1...G<....[...~i.....xp.ar.....n...|....W......B+...z.+c5 ....B.N...>.R...zX.....~.s..J..............0..r.6.5....?L>...........V4&...Z.,uWWWNVl.l7:.0..}Jv....:....=...H..>...2p.z..(..W.:......D..X.I'.a../H....(9.o..6[..G..9..p.kq._. ....&..$C.r...2y:!.d].....`…Y.|.D.~d…S.K…\>}…V.m…%…\<…-wE…’  
?.#1…1NZ.p…'=.{…Ic^…4…E5…lWf.x}.n.JT…{…iU-…y…5[.+a…2…J…?I…//…\*e4a.i…I/9.^…NR…i.M…i3}:…

## 

T 10.102.38.165:80 → 10.102.38.185:42920 [AP]  
.?A…H…Q…?z.‘…6…L…]9…)…a\_.:]B.X…K…RO.eQ…7.ko.$R.C…P.8…,.$…@.[.E$L…q.e.%8…cY…c#.  
.K…~!’…Y.-.v…}^…t.7.N1.t;.x.vq…(^…=…E|…/…R.;…l\<…0/.+t…q\_.?}…J…/.56.A…`…Ad…2g…0.9.2…=…&…X…4…1…u…QhqIQ='…@7z…0…+…

### 

T 10.102.38.185:80 → 24.227.153.188:54091 [A]  
HTTP/1.1 404 Not Found.  
Server: nginx/0.7.65.  
Date: Thu, 20 Jan 2011 01:14:02 GMT.  
Content-Type: text/css.  
Transfer-Encoding: chunked.  
Connection: keep-alive.  
Last-Modified: Wed, 19 Jan 2011 22:20:44 GMT.  
Expires: Sun, 17 Jan 2021 01:14:02 GMT.  
Cache-Control: max-age=315360000.  
Content-Encoding: gzip.  
.  
b86.  
…ZYo.H.~…E#~.n`..iIF..$.......b..@h.-.0E $.c.........{... ............?............}~.~.....`….y…?.._|?Z.N.z.\>…$.=…I…%…U…U…D.:a5_…~.nE…e…V…V.L…rs…YQ…d6…D.Z…Z…D.E…y…  
…)e…7…][yD.tV](http://yD.tV)[^…1\*J.=?#6{q&`.d.G..s...^_...2+x]-2..q.~...t.K.....4!.vbQ.u&`.1I.;.%…/…E…0I.m…o…4…]u…!..+…\<{…$.Ws6.Av.Q\<…UE.&…J)M..?y7._…#k.m].@…H.:.P.G.j…X\_Q…+.v+…10Z…-.y…xy}./…+…Eo.-.\<…Q…P….…&…  
…“…$.9\<.I.O.H?..?.)…Ed…Ncp…].U.E…47…:.t…r~…x…i…X…h…E.]…d…gh3uLo:…](…(”.c.1…:y.=T…i’…3iW.E.Q(.XB…PC…o.W…b…t…[…6\Q.io…H…D…Q…/…M  
.5k.p@S.}.o\<…[.h!k.$.Q4.‘…wiR.I…C…2…Z…L…a…Fs…B…hHo8…c.d…HxK9…’{…%}…h…e.z.\>…?._…^.,(.c  
…X2…t…P.Q.s)…N]…$.1.?..@…,s…Z…1X…M…pF…d.,…a…y…l.P…R.'(h.  
…Ek…N…G…O$…#…k…L.t…4=…E^1r.&…SK)…[].X…_j(.U…V.V1H…gQ…u.Nk…m.7&…L.M…|K.H…,8…I8…J…y.F…0…T.4.  
x.,!..b.O…&…q.9.f.u…E…\<…8…8.A…B&@.&…/…]…OX.~.+nR.z,n…_…{  
…{S…]L…`.......LoG..[3..3.W|.f...t]......}/..X..5.P...Q.w.b.P..Ix.e(.h.T.0.......y.....l[..J...a2..>.R.{%e .,removed_email_address@domain.invalid....[..5.../p...;..Uu.....Y....t4.D._.K..'.U....R.z.*..+...Kp.....L"......"...tb...0.uB..p$+.@D5.{..+Uk..*....M.?[4..D....S.^~x..a ..J.F+.i'...=L2._.........X...._.....2..]..k...o(.lp....\....\)...*....T.......L.O..z...Z9.......RP/I.&......(...q.7[.Pb!..7.>...<./..'.P....c"...A..c .sf8..........d.MA.;`…H…6.ut2K…@…g7…P…6.3p…Z…"…l…}V60.x.y.#…)y.P…X…C}.t…9…7…b…)9.T…m…^7.%…2!~L…1R…%…:uBt.3…@…B…&.d…r:…`.A..'..B.y.......|........F...b....n.@.../.y.O.$v.)....u*B..P......f..x8nD.6...T..z.L.{.j...|..#...b......M.u...|)td........G...B.$.wp>6@q6.8.0.P&j..].l.w..A....+....%N......h....@.x.C.%i.....:Y].._.l......./,..Q..Lj....|+)...........7.-R.....(..].C......D$..pq.c@.K.......... ..2..k....$e.P.... .v..r....U.sx...]...$$$ .4.&.........G.....-...o1...G<....[...~i.....xp.ar.....n...|....W......B+...z.+c5 ....B.N...>.R...zX.....~.s..J..............0..r.6.5....?L>...........V4&...Z.,uWWWNVl.l7:.0..}Jv....:....=...H..>...2p.z..(..W.:......D..X.I'.a../H....(9.o..6[..G..9..p.kq._. ....&..$C.r...2y:!.d].....`…Y.|.D.~d…S.K…\>}…V

# 

T 10.102.38.185:80 → 24.227.153.188:54091 [AP]  
.m…%…\<…-wE…’  
?.#1…1NZ.p…‘=.{…Ic^…4…E5…lWf.x}.n.JT…{…iU-…y…5[.+a…2…J…?I…//…\*e4a.i…I/9.^…NR…i.M…i3}:…?A…H…Q…?z.’…6…L…]9…)…a\_.:]B.X…K…RO.eQ…7.ko.$R.C…P.8…,.$…@.[.E$L…q.e.%8…cY…c#.  
.K…~!‘…Y.-.v…}^…t.7.N1.t;.x.vq…(^…=…E|…/…R.;…l\<…0/.+t…q\_.?}…J…/.56.A…`…Ad…2g…0.9.2…=…&…X…4…1…u…QhqIQ=’…@7z…0…+…

#### 

T 10.102.38.185:80 → 24.227.153.188:54091 [AP]  
0.  
.

######################################################

nginx.conf:

user involver;  
worker\_processes 4;  
pid /var/run/nginx.pid;  
worker\_rlimit\_nofile 10240;

events {  
worker\_connections 8192;  
use epoll;  
}

http {

include /etc/nginx/mime.types;

default\_type application/octet-stream;

log\_format main '$remote\_addr - $remote\_user [$time\_local] ’  
'“$request” $status $body\_bytes\_sent “$http\_referer”  
’  
‘“$http\_user\_agent” “$http\_x\_forwarded\_for”’;

# main access log

access\_log /data/nginx/log/nginx\_access.log main;

# main error log

error\_log /data/nginx/log/nginx\_error.log debug;

sendfile on;

tcp\_nopush on;

include /etc/nginx/apps/\*.conf;

}

##########################################

apps/involver-cache-server.conf ([test5.involver.com](http://test5.involver.com) is the app server):

upstream switching\_backend {  
server localhost:81 weight=100;  
server [test5.involver.com](http://test5.involver.com);  
}

upstream rails\_backend {  
server [test5.involver.com](http://test5.involver.com);  
}

upstream cache\_backend {  
server localhost:8190;  
server localhost:8191;  
server localhost:8192;  
server localhost:8193;  
}

server {  
listen 80 default;  
server\_name \_;  
root /data/apps/involver-cache-server/current/public;

# Fail fast with a 404 for server pages that rails backend will never

serve  
location ~\* .(php|jsp|asp|aspx|cfm|pl|py|tpl)$ { return 404; }

include /etc/nginx/common/app.conf;  
include /etc/nginx/common/proxy.conf;

location = /file\_uploads {  
client\_max\_body\_size 200m;  
proxy\_pass http://rails\_backend;  
break;  
}

location ~\* /rest/features/(._)/content\_items/(._)/images {  
proxy\_pass http://rails\_backend;  
break;  
}

location /assets/audio\_uploads { return 404; }  
location /assets {  
proxy\_pass http://rails\_backend;  
break;  
}

location /cache {  
proxy\_pass http://rails\_backend;  
break;  
}

location / {  
proxy\_next\_upstream http\_404 http\_500 http\_502 http\_503 http\_504  
error timeout;  
proxy\_pass http://switching\_backend;  
}

}

# OFFLOADED SSL

server {  
listen 88;  
server\_name \_;  
root /data/apps/involver-cache-server/current/public;

# Fail fast with a 404 for server pages that rails backend will never

serve  
location ~\* .(php|jsp|asp|aspx|cfm|pl|py|tpl)$ { return 404; }

include /etc/nginx/common/app.conf;  
include /etc/nginx/common/proxy.conf;

proxy\_set\_header X-FORWARDED\_PROTO https;

location ~\* /rest/features/(._)/content\_items/(._)/images {  
proxy\_pass http://rails\_backend;  
break;  
}

location /assets/audio\_uploads { return 404; }  
location /assets {  
proxy\_pass http://rails\_backend;  
break;  
}

location /cache {  
proxy\_pass http://rails\_backend;  
break;  
}

location / {  
proxy\_next\_upstream http\_404 http\_500 http\_502 http\_503 http\_504  
error timeout;  
proxy\_pass http://switching\_backend;  
}  
}

# CACHING HANDLER

server {  
listen 81;  
server\_name \_;  
root /data/apps/involver-cache-server/current/public;

include /etc/nginx/common/proxy.conf;

location / {  
proxy\_pass http://cache\_backend;  
}  
}

#############################################

common/app.conf:

# Max size for file uploads

client\_max\_body\_size 100M;

# This allows people to use images and css in their maintenance.html

file  
if ($request\_filename ~\* .(css|jpg|gif|png)$) {  
break;  
}

# Rewrite all the requests to the maintenance.html page if it exists.

if (-f $document\_root/system/maintenance.html) {  
return 503;  
}

error\_page 404 /404.html;  
error\_page 500 502 504 /500.html;

error\_page 503 @503;  
location @503 {  
rewrite ^(.\*)$ /system/maintenance.html break;  
}

##################################################

common/proxy.conf:

index index.html index.htm;

# needed to forward user’s IP address to rails

proxy\_set\_header X-Real-IP $remote\_addr;  
proxy\_set\_header X-Forwarded-For $proxy\_add\_x\_forwarded\_for;  
proxy\_set\_header Host $http\_host;

proxy\_redirect off;  
proxy\_max\_temp\_file\_size 0;

server\_name\_in\_redirect off;

# set Expire header on assets: see

> **[Best Practices for Speeding Up Your Web Site - Yahoo Developer Network](https://developer.yahoo.com/performance/rules.html)**
>
> The Exceptional Performance team has identified a number of best practices for making web pages fast.

location ~ ^/(images|javascripts|stylesheets)/ {  
expires 10y;  
}

# serve any existing file

if (-f $request\_filename) {  
break;  
}

# serve any standard Rails page cache file with .html extension

if (-f $request\_filename.html) {  
rewrite (.\*) $1.html break;  
}

Posted at Nginx Forum:

> **[Problem with Nginx returning correct content, but with 404](https://forum.nginx.org/read.php?2,167927,167927#msg-167927)**
>
> Hello, We have a setup where we have requests coming into a cache server which is in front of an app server. The requests hit nginx on the cache server, which makes the request to a process running on the cache server. That process will return either...

---

<div class="post-metadata">

**Author:** ![austinmills](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/db5fbb/32.png) [@austinmills](https://www.ruby-forum.com/u/austinmills)\
**Post date:** [January 20, 2011, 5:57pm UTC](https://www.ruby-forum.com/t/problem-with-nginx-returning-correct-content-but-with-404/202054/2 "2011-01-20T17:57:37Z")

</div>

Hello!

On Thu, Jan 20, 2011 at 11:23:17AM -0500, austinmills wrote:

> form /admin/fan\_pages, but when requesting css or png content (like  
> /stylesheets/common.css , or /images/admin/fan\_pages/refresh.png ), it  
> is returning the correct content, but with a 404 code. In this case, the  
> local process on the cache server is returning a 404, the nginx on the  
> cache server is requesting the page from the app server (which returns  
> the page with a 200), but then the cache server is turning around and  
> serving the correct content to the client with a 404.
> 
> Anybody have any ideas on how/why this is happening? I’ll include config  
> files and output below. If there’s a simpler or better setup to  
> accomplish what we’re trying to do, I’m happy to try that as well.

Request to /stylesheets/common.css will generate 404 as long  
as you don’t have static file on disk, as it’s matched by this  
location in your config:

> # set Expire header on assets: see

> **[Add an Expires or a Cache-Control Header - Best Practices for Speeding Up Your...](https://developer.yahoo.com/performance/rules.html#expires)**
>
> The Exceptional Performance team has identified a number of best practices for making web pages fast. The list includes 35 best practices divided into 7 categories. | The Exceptional Performance team has identified a number of best practices for...

> location ~ ^/(images|javascripts|stylesheets)/ {  
> expires 10y;  
> }

You have 404 error\_page set without overwriting status code:

> error\_page 404 /404.html;

I.e. 404 code will be preserved regardless of future processing.  
This explains 404 status code.

Future processing will happen here:

> location / {  
> proxy\_next\_upstream http\_404 http\_500 http\_502 http\_503 http\_504 error  
> timeout;  
> proxy\_pass http://switching\_backend;  
> }

As proxy\_pass without uri component is used, it will preserve  
original request uri when asking backend. This explains correct  
content.

Maxim D.

---

<div class="post-metadata">

**Author:** ![austinmills](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/db5fbb/32.png) [@austinmills](https://www.ruby-forum.com/u/austinmills)\
**Post date:** [January 20, 2011, 6:05pm UTC](https://www.ruby-forum.com/t/problem-with-nginx-returning-correct-content-but-with-404/202054/3 "2011-01-20T18:05:48Z")

</div>

Maxim,

That was exactly it. I removed the location and all is well. Many  
thanks!

–Austin

Posted at Nginx Forum:

> **[Re: Problem with Nginx returning correct content, but with 404](https://forum.nginx.org/read.php?2,167927,167954#msg-167954)**
>
> Hello, We have a setup where we have requests coming into a cache server which is in front of an app server. The requests hit nginx on the cache server, which makes the request to a process running on the cache server. That process will return either...