# Troubleshooting Zulip uses [Supervisor](http://supervisord.org/index.html) to monitor and control its many Python services. Read the next section, [Using supervisorctl](#using-supervisorctl), to learn how to use the Supervisor client to monitor and manage services. If you haven't already, now might be a good time to read Zulip's [architectural overview](../overview/architecture-overview.html), particularly the [Components](../overview/architecture-overview.html#components) section. This will help you understand the many services Zulip uses. If you encounter issues while running Zulip, take a look at Zulip's logs, which are located in `/var/log/zulip/`. That directory contains one log file for each service, plus `errors.log` (has all errors), `server.log` (has logs from the Django and Tornado servers), and `workers.log` (has combined logs from the queue workers). The section [troubleshooting services](#troubleshooting-services) on this page includes details about how to fix common issues with Zulip services. If you run into additional problems, [please report them](https://github.com/zulip/zulip/issues) so that we can update this page! The Zulip installation scripts logs its full output to `/var/log/zulip/install.log`, so please include the context for any tracebacks from that log. ## Using supervisorctl To see what Zulip-related services are configured to use Supervisor, look at `/etc/supervisor/conf.d/zulip.conf` and `/etc/supervisor/conf.d/zulip-db.conf`. Use the supervisor client `supervisorctl` to list the status of, stop, start, and restart various services. ### Checking status with `supervisorctl status` You can check if the zulip application is running using: ``` supervisorctl status ``` When everything is running as expected, you will see something like this: ``` process-fts-updates RUNNING pid 2194, uptime 1:13:11 zulip-django RUNNING pid 2192, uptime 1:13:11 zulip-senders:zulip-events-message_sender-0 RUNNING pid 2209, uptime 1:13:11 zulip-senders:zulip-events-message_sender-1 RUNNING pid 2210, uptime 1:13:11 zulip-senders:zulip-events-message_sender-2 RUNNING pid 2211, uptime 1:13:11 zulip-senders:zulip-events-message_sender-3 RUNNING pid 2212, uptime 1:13:11 zulip-senders:zulip-events-message_sender-4 RUNNING pid 2208, uptime 1:13:11 zulip-tornado RUNNING pid 2193, uptime 1:13:11 zulip-workers:zulip-deliver-enqueued-emails STARTING zulip-workers:zulip-events-confirmation-emails RUNNING pid 2199, uptime 1:13:11 zulip-workers:zulip-events-digest_emails RUNNING pid 2205, uptime 1:13:11 zulip-workers:zulip-events-email_mirror RUNNING pid 2203, uptime 1:13:11 zulip-workers:zulip-events-error_reports RUNNING pid 2200, uptime 1:13:11 zulip-workers:zulip-events-feedback_messages RUNNING pid 2207, uptime 1:13:11 zulip-workers:zulip-events-missedmessage_mobile_notifications RUNNING pid 2204, uptime 1:13:11 zulip-workers:zulip-events-missedmessage_reminders RUNNING pid 2206, uptime 1:13:11 zulip-workers:zulip-events-signups RUNNING pid 2198, uptime 1:13:11 zulip-workers:zulip-events-slowqueries RUNNING pid 2202, uptime 1:13:11 zulip-workers:zulip-events-user-activity RUNNING pid 2197, uptime 1:13:11 zulip-workers:zulip-events-user-activity-interval RUNNING pid 2196, uptime 1:13:11 zulip-workers:zulip-events-user-presence RUNNING pid 2195, uptime 1:13:11 ``` ### Restarting services with `supervisorctl restart all` After you change configuration in `/etc/zulip/settings.py` or fix a misconfiguration, you will often want to restart the Zulip application. You can restart Zulip using: ``` supervisorctl restart all ``` ### Stopping services with `supervisorctl stop all` Similarly, you can stop Zulip using: ``` supervisorctl stop all ``` ## Troubleshooting services The Zulip application uses several major open source services to store and cache data, queue messages, and otherwise support the Zulip application: * postgresql * rabbitmq-server * nginx * redis * memcached If one of these services is not installed or functioning correctly, Zulip will not work. Below we detail some common configuration problems and how to resolve them: * An AMQPConnectionError traceback or error running rabbitmqctl usually means that RabbitMQ is not running; to fix this, try: ``` service rabbitmq-server restart ``` If RabbitMQ fails to start, the problem is often that you are using a virtual machine with broken DNS configuration; you can often correct this by configuring `/etc/hosts` properly. * If your browser reports no webserver is running, that is likely because nginx is not configured properly and thus failed to start. nginx will fail to start if you configured SSL incorrectly or did not provide SSL certificates. To fix this, configure them properly and then run: ``` service nginx restart ``` * If your host is being port scanned by unauthorized users, you may see messages in `/var/log/zulip/server.log` like ``` 2017-02-22 14:11:33,537 ERROR Invalid HTTP_HOST header: '10.2.3.4'. You may need to add u'10.2.3.4' to ALLOWED_HOSTS. ``` Django uses the hostnames configured in `ALLOWED_HOSTS` to identify legitimate requests and block others. When an incoming request does not have the correct HTTP Host header, Django rejects it and logs the attempt. For more on this issue, see the [Django release notes on Host header poisoning](https://www.djangoproject.com/weblog/2013/feb/19/security/#s-issue-host-header-poisoning)