<p>If the system recently rebooted and your proxy server is giving 502/503s, it's most likely that the backend service failed to start.</p>

<p>Using whatever tools are most appropriate for your OS/distro (e.g. <code>systemctl</code>, <code>service</code>/<code>chkconfig</code>, <code>stop</code>/<code>start</code>/<code>restart</code>/etc.), do the following things:</p>

<ul>
<li>Verify that the backend (in this case Jenkins) is configured to start on boot.  Enable it if not.</li>
<li>Start the backend.</li>
<li>If the backend fails to start, check the application logs to find the source of the error.  For Jenkins on Linux, this would be <code>/var/log/jenkins/jenkins.log</code>.</li>
</ul>

CC BY-SA 3.0
2018-03-28T07:50:30.950Z
All the services, nginx and jenkins are up and running, jenkins is started on boot, but still I got the same errors.
spacetrack
CC BY-SA 4.0
2019-11-03T03:08:39.433Z
same here, i know it's been a long time since this has been posted, but have you found the solution?
Joseph K.
CC BY-SA 4.0
2020-09-24T09:47:07.243Z
@JosephK. did you find a solution?
FooBar
CC BY-SA 3.0
2018-03-27T15:59:19.100Z
2018-03-27T15:59:19.100Z
jayhendren
<p>So my server got maintenance schedule from cloud provider, after maintenance process, the server rebooted, then my jenkins cannot be accessed from the web anymore, I am using nginx and checking the logs I found this.</p>

<blockquote>
  <p>/var/log/nginx/error.log</p>
</blockquote>

<pre><code>2018/03/26 16:11:00 [error] 21689#21689: *1 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 139.139.139.139, server: jenkins.domain.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:8080/", host: "jenkins.domain.com"

2018/03/26 16:11:00 [error] 21689#21689: *1 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 139.139.139.139, server: jenkins.domain.com, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:8080/favicon.ico", host: "jenkins.domain.com", referrer: "http://jenkins.domain.com/"
</code></pre>

<p>here is my nginx conf file:</p>

<pre><code>upstream app_server {
server 127.0.0.1:8080 fail_timeout=0;
}



server {
  listen 80;
  server_name jenkins.domain.com;
  root /var/www/jenkins.domain.com;

  location ~ /\.well-known/acme-challenge {
        default_type "text/plain";
  }

  location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;

        if (!-f $request_filename) {
            proxy_pass http://app_server;
            break;
        }
    }
}
</code></pre>

<p>What is the cause of this and maybe what can I do to fix this? Really need your help guys.</p>

<p>Thanks</p>

CC BY-SA 4.0
2019-04-11T14:12:23.690Z
Got same problem. Did you find a solution? I tried already most of the stuff that come up on google, but still struggling
Lukino
CC BY-SA 4.0
2020-09-24T09:46:49.913Z
@Lukino did you ever find a solution?
FooBar
CC BY-SA 4.0
2020-09-25T18:37:45.060Z
@FooBar Hmm, it is a while, but I managed to get my Jenkins running behind Nginx. (to be a little bit more specific, I got Nginx, Jenkins and Nexus running as Docker containers on the Physical server...
Lukino
<jenkins><nginx>
Jenkins returns 502 gateway error and (104: Connection reset by peer)
spacetrack
# Jenkins returns 502 gateway error and (104: Connection reset by peer)

(Asked by: username_0 on 2018-03-27)

So my server got maintenance schedule from cloud provider, after maintenance process, the server rebooted, then my jenkins cannot be accessed from the web anymore, I am using nginx and checking the logs I found this.

/var/log/nginx/error.log

2018/03/26 16:11:00 [error] 21689#21689: *1 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 139.139.139.139, server: jenkins.domain.com, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:8080/", host: "jenkins.domain.com"

2018/03/26 16:11:00 [error] 21689#21689: *1 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 139.139.139.139, server: jenkins.domain.com, request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:8080/favicon.ico", host: "jenkins.domain.com", referrer: "http://jenkins.domain.com/"

here is my nginx conf file:
upstream app_server {
server 127.0.0.1:8080 fail_timeout=0;
}



server {
  listen 80;
  server_name jenkins.domain.com;
  root /var/www/jenkins.domain.com;

  location ~ /\.well-known/acme-challenge {
        default_type "text/plain";
  }

  location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;

        if (!-f $request_filename) {
            proxy_pass http://app_server;
            break;
        }
    }
}

What is the cause of this and maybe what can I do to fix this? Really need your help guys.
Thanks

**Tags:** jenkins, nginx

> **Comments:**
> **username_1**: Got same problem. Did you find a solution? I tried already most of the stuff that come up on google, but still struggling  
> **username_2**: @username_1 did you ever find a solution?  
> **username_1**: @username_2 Hmm, it is a while, but I managed to get my Jenkins running behind Nginx. (to be a little bit more specific, I got Nginx, Jenkins and Nexus running as Docker containers on the Physical server...  

---

## 1 answers

### Answer by username_3 on 2018-03-27. Score: 2 | Accepted answer

If the system recently rebooted and your proxy server is giving 502/503s, it's most likely that the backend service failed to start.

Using whatever tools are most appropriate for your OS/distro (e.g. `systemctl`, `service`/`chkconfig`, `stop`/`start`/`restart`/etc.), do the following things:

* Verify that the backend (in this case Jenkins) is configured to start on boot. Enable it if not.
* Start the backend.
* If the backend fails to start, check the application logs to find the source of the error. For Jenkins on Linux, this would be `/var/log/jenkins/jenkins.log`.

> **Comments:**
> **username_0**: All the services, nginx and jenkins are up and running, jenkins is started on boot, but still I got the same errors.  
> **username_4**: same here, i know it's been a long time since this has been posted, but have you found the solution?  
> **username_2**: @JosephK. did you find a solution?  

---

