What’s Causing My Timeouts?

When outages are short (i.e. under 2 minutes), they are most likely caused by a temporary issue somewhere between Testomatobot and your site. The cause of this type of issue can be hard to determine.

This article will teach you about timeout results you may see in Reports and where to start when trying to discover the exact source of a problem.


Timeouts make up over 70% of the short incidents we see reported by Testomato.

Most of the time, timeouts occur during peak hours when you have high visitor traffic. However, another common reason is that your hosting service or server reaches aconcurrent connection limit.

A concurrent connection is how many people are calling a task on your website at one time. When someone clicks on a page, and then submits a form on your website, these are considered two separate consecutive actions that require two separate consecutive connections.

However, when 50 people click on the same page at the same time, these are considered 50 concurrent connections. After the page loads, the connection closes.

Hosting services often limit the number of concurrent connections to a site to avoid an overload of processes, or how many visitors can simultaneously connect to your hosting account at one time.

Testomato opens a concurrent connection for every check that it runs on your site, and in some cases this can cause a page to be unavailable when we try to test it.

What can you do to avoid this problem?

We have a few suggestions:

Increase your timeout period and delay

Set a longer delay period between subsequent checks to avoid an overlap from Testomato and increase Timeout settings.

To adjust these periods, open your project and then click to Project Settings

Project Settings

and scroll down to Advanced options:

Advanced options

Change email notifications delay

Delay your email notifications to avoid receiving alerts about short-term issues. You can delay your notifications from your account Instant Notifications Settings and change

Sent email notifications settings:
Sent Email Notifications

HTTP Status Codes

Roughly 15% of short incidents are related to server responses with error code. Many of these can be general, which can make it harder for you to track down the error on your website.

Here’s a quick look at the three most common status codes we see in Testomato and possible reasons you might see them:

  • 503 Service Unavailable – Your backend was unable to handle all the requests made to your site. As a result, your proxy will start returning 503 errors.
  • 500 Internal Server Error – This is a very general server error, so the best place to check for more clues about the problem is your application log. These errors are often connected with availability issues and timeouts related to your database server, or other important services your application needs to run.
  • 502 Bad Gateway Error – These errors are usually protocol problems between your proxy and backend server due to maintenance.

PHP Fatal Error – Out of Memory

About 5% of the reported incidents in Testomato are related to PHP errors. You can find full details about each error in your Issues Timeline located in your project’s Reports tab.

However, the PHP error we see the most in Testomato is Fatal Error: Out Of Memory. This is a particularly common if your application processes large amounts of data.

This message means you’re trying to load more memory than you have available in the system.

We suggest evaluating the other processes that run on your server and how much memory they consume. Increase your system memory accordingly, and then optimize or remove greedy programs (like your database) to another server.

If you’re running on Apache, you might want to take a second look at how its configured. Try getting rid of unnecessary modules, set lower MaxClients, and limit MaxRequestsPerChild to prevent memory leaks. You could also try migrating to a web server with better memory management, such as nginx or IIS.

Download Errors

Download errors are usually caused by Network, SSL, or DNS problems.

Let’s take a look at the most common errors we send to Testomato users:

  • Failed to connect to host (Connection refused): This message means that Testomatobot was unable to connect to your server and is getting refused by a firewall. If you filter your traffic, check your firewall configuration and be sure to allow access to Testomatobot’s IP addresses.
  • Downloading content failed (Connection reset by peer): This message means the connection was terminated before the page could finish downloading. This is often related to maintenance work on your server, such as a software upgrade or a server restart by the server administrator. It could also be caused by general server failures like segmentation faults.
  • Failed to connect to host (No route to host): This message means there was a routing problem and Testomatobot was unable to connect to your server. Unfortunately, this could occur anywhere between your server and Testomato, but the good news is that this is usually related to a short-term network problem.