Monitoring & Analyzing Error Pages (404s) Using Analytics

I recently wrote a post on the Google Analytics + page about monitoring error pages on websites. The post was well received and generated a healthy discussion on Google+, so I decided to write a more detailed article on the subject here.

First of all, what exactly is an error or 404 page? According to Wikipedia “The 404 or Not Found error message is a HTTP standard response code indicating that the client was able to communicate with the server, but the server could not find what was requested.” Or, in more general terms, the 404 is the error you get when the page you are looking for does not exist, usually because the link you clicked was broken.

Another important question is: why should I care? Often times the 404 is forgotten and no one cares to prioritize its optimization. I believe the answer to prioritization lies on section 2 of this post: by monitoring the percentage of users that arrive at this page you will be in a better position to know if (and how quickly) you should optimize your 404 page. In any case, even if the number of people viewing this page is low, you should at least have a page in the lines of your brand and try to add the elements described in section 1 below; after all, you don’t want to disappoint your customers!

In this post I propose a few techniques to help improve error pages, engage visitors and improve the website experience. The questions I will try to answer are the following:

1. How to build your 404 page?


2. How to monitor your 404 page traffic efficiently?


3. How to analyze & optimize 404 page success?

1. Error Pages Best Practices

Before we dive into Google Analytics, let’s take a look into some ways to create a great 404 page from the beginning. Following are some good usability insights proposed in a book called Defensive Design for the Web. The authors advise us to offer customized "Page Not Found" error pages; and they provide an interesting insight into how to create error pages:

Instead of merely saying a page is not found, your site needs to explain why a page can't be located and offer suggestions for getting to the right screen. Your site should lend a hand, not kick people when they are down. Smart things to include on your 404 page:

1. Your company's name and logo


2. An explanation of why the visitor is seeing this page


3. A list of common mistakes that may explain the problem


4. Links back to the homepage and/or other pages that might be relevant


5. A search engine that customers can use to find the right information


6. An email link so that visitors can report problems, missing pages, and so on

2. Monitoring Error Page Traffic

Suppose a prominent blog links to your site and the link is broken, this will cause a negative experience to users (which will not find what they expected) and to search engines (which will not crawl the right content). How long will it take until you notice it? How often do you check the traffic to your 404 page? Chances are you don’t do it every day, but you should! Or at least you should have someone look at it: why not let Google Analytics do it for you? 

Create an Alert on Google Analytics

In the screenshot below you will see how to set an alert on Google Analytics that will let you know each time your 404 pageviews increases above a certain threshold. This will enable you to do the work once and be alerted every time there is a problem. 

The alert below is based on the increase in error pageviews, but if you decide to create a goal (as suggested below) you could create the alert based on the goal too. Note that you can opt in to receive an email or a text message when the condition is met (404 pageviews increases more than 15% compare to previous day). Also note that I decided to define the 404 page based on the title of the page, very often there is no indication of an 404 page on the URL (read more about this below). 

To learn how to set a Custom Alert check this help center article.

Measure your 404 Page as a Goal

Setting the 404 page as a goal on Google Analytics will surface important information that can be achieved only through goals, e.g. the last three steps before getting to this page. Below is a screenshot on how to do it, but note that you would need to have an identifier on your URL (or trigger an event) in order to set your 404 as a Goal.

Add Your 404 Content Report to Your Dashboard

Every report on Google Analytics can be added to the dashboard. By adding the 404 page to your dashboard you will be able to constantly monitor the trend of visits to your 404 page. Learn more about customizing dashboards.

3. Analyzing & Optimizing Error Pages

Monitoring your 404 pages is important, but useless if you don't take action using this information. Taking action means doing all you can to decrease the number of people getting missing pages. Below I provide a few tips on how to find and fix both internal and external broken links.

Check Your Navigation Summary Report

This will help you understanding where did visitors come from from inside your site, i.e. it will tell you which pages contain internal broken links. You will also be able to understand what is the percentage of visitors that arrive to the 404 page from internal and external sources; the internal sources will be listed on this report. See navigation summary screenshot below:

Check 404 Page URLs

Learning which URLs are producing the errors is a great way to get rid of them. If you learn, for example, that 100 visitors a day get an error when they visit the page “/aboutS” you can infer that there is a broken link leading to it; sometimes it might not be possible to find the source of the error to fix the link, but you can add a redirect from that page to “/about”, which looks to be the right page. 

In order to do that you will need to find the report below, but please keep in mind that some assumptions were made to arrive at it. Most CMS (Wordpress, Drupal, and others) will return an error for non-existing pages on the actual content section, but they will keep the original URL; however, they will have a page title with the word 404 in it. So check your site to know if that is the case before you try the report below.

Once you find this report, click on the first entry and you will get a list of all the URLs that triggered an error page. Good luck with the redirects!

Measure Internal Searches From this Page

If you do not have a search box on your 404 page, you should seriously consider adding one. Through searches performed in this page you will be able to understand what people were expecting to find there and you will get insights on which links you should add to the page. If you don’t have Internal Site Search enabled on Google Analytics check this help center article.

Below are the metrics you will be able to analyze if you use this feature:

• Total Unique Searches: the number of times people started a search from the 404 page. Duplicate searches within a single visit are excluded.


• Results Pageviews/Search: the average number of times visitors viewed a search results page after performing a search.


• % Search Exits: the percentage of searches that resulted in an immediate exit from your site.


• % Search Refinements: the percentage of searches that resulted in another search (i.e. a new search using a different term).


• Time after Search: The average amount of time visitors spend on your site after performing a search.


• Search Depth: The average number of pages visitors viewed after performing a search.

Closing Thoughts

As we mentioned above, errors happen, and we must be prepared for them. We must give a hand to our visitors when they are most frustrated and help them feel comfortable again. The level of online patience and understanding is decreasing and users have a world of choices just one click away, so website owners cannot let one small error get on their way.

Posted by Daniel Waisberg, Analytics Advocate