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Getting to grips with the technical elements of your site will no doubt see you encounter status codes; it’s important to understand them so that they don’t affect your user’s experience on your site, or your website’s crawlability for search engines. In this article, we’re going to delve into one code in particular - the downtime code 503. Here’s everything you need to know…

What are status codes?

HTTP status codes are returned every time you access a website; you’re just not aware of them until you encounter one that means there’s a problem. We’ve written before about what status codes mean, but basically, your computer requests a three-digit code from the website’s server when it tries to access it in order to get its status.

For example, your browser receiving a 200 code means that it’s all okay to proceed; a code that starts with a 3 means the page has moved either temporarily or permanently, and one that starts with a 4 means the page couldn’t be found, or the content has been deleted - the most common is a 404 error.

If a server status code 503 is returned, it means that there’s maintenance happening on the site; this is the code we’ll be talking about today.

The role of HTTP status codes in SEO

It’s not just browsers that understand HTTP status codes; Google can, too. For example, when its crawlers come across a 404 error, it’ll discard that page from the search results, which is why redirects are so important. It’ll return to the page a few times before abandoning its next crawl for a while, since it deems it a waste of time if it keeps 404-ing on them, meaning a big impact on the performance of the page when it gets back up and running.

In short, Google can tell a lot about the usability and overall health of your site by what codes it comes across; the user experience will also be negatively impacted by HTTP ‘error’ codes, and therefore you’ll be marked down by Google.

What is a 503 status error?

If 404s damage your SEO, what happens when you need the page to be unavailable because you’re working on it? This is where 503s come in; they signal that your website is currently experiencing downtime, but will be back soon.

What causes website downtime?

Website downtime is generally caused by page maintenance, a server update, or an unplanned outage.

The impact of website downtime - and importance of website uptime

Only if your website experiences outages of more than around 10-15 minutes a few times a week should you start to expect various elements of your SEO to be affected. But even so, you’d really rather not have ‘503 service unavailable’ messages that frustrate both your user and Google. Here are some things that can be affected by repeated and/or severe website downtime:


What happens when you’re searching for something online, and you come across an error? You move on to a competitor. Do you return to that original site? Unlikely - they’re already lodged in your mind as a site that can’t help you when you need it. This is how your user experience is affected by downtime – they’ll simply go elsewhere!

Crawling and indexing issues

It’s not just users that will move onto the next; Google will too. If its crawlers repeatedly come across errors on your site, the page will have a harder time getting indexed.

Page rank and search visibility issues

This leads on from crawling and indexing issues; if Google is struggling to discover, understand, and index your page (which means it adds it to its database from which it chooses pages to present to users based on relevance), your rankings will naturally go down. Lower search visibility is bad news for traffic and, ultimately, conversions.

Loss of trust and credibility

Google has made its preferences very clear when it comes to what they look for in website content - Expertise, Experience, Authority, and Trust. Can your website be trusted not to go down frequently? Repeated error messages may tell them that it can’t, and it’s something your users will begin to know you for too - you’re losing credibility!

Loss of web traffic

A page that isn’t visible simply doesn’t get traffic on it that stays - this will show up in your performance and engagement metrics, skewing your data and making it harder to see where improvements can be made (beyond making sure your site goes down less, obviously).

Do 503 errors affect SEO?

If they happen repeatedly for significant periods of time, then yes, 503 errors affect your SEO - if Google can’t get to your page to crawl it, it won’t index it, and therefore you’ll lose rankings, or fail to be ranked altogether.

How can you minimise the effects of downtime?

Plan your website updates

Sporadic and unplanned updates could affect your user’s experience as well as your website’s crawlability, so minimise this impact with careful planning. Strategies that include gradual rollouts of updates and carrying out updates at night in the country you get the most traffic from helps mitigate frustration caused by downtime.

Implement a 503 status code

Where planned updates are happening, make sure to implement a 503 status code, instead of blocking web crawlers with robots.txt or redirecting away from the website. 503 errors show the search engine that the website is temporarily down; they’ll know to come back later to see if there is an update, so that impact on your rankings is kept as low as possible.

Retry-after HTTP header

There is a way to tell Google that you won’t be gone for long; by implementing a ‘Retry-After’ header within your HTML, you’ll be telling Google how many minutes to wait before returning to the page. That doesn’t mean Google is guaranteed to return after the exact amount of time you tell them to, it’ll just prevent them from returning before this time.

Communicate to users

An email or a banner on your site that tells users about planned maintenance can help them anticipate some temporary loss of service, minimising the impact on how they interact with your site.

Server redundancy or load balancing

Using one or more server ‘paths’ helps redirect traffic if one path fails - meaning that some server downtime doesn’t necessarily mean a complete loss of service.

Use monitoring tools

Pay close attention to your stats through services such as GA4 throughout the downtime, so that you know how much users are impacted during times when your website is unavailable.

What about WordPress and plugins?

Wordpress has your back in times like this; it will automatically return a ‘503 service temporarily unavailable error when updating plugins or WordPress core. You can also use a specific maintenance plugin such as WP Maintenance Mode, which enables you to use advanced features to help manage your website’s downtime.

Need help with your website updates?

Managing 503 errors, and HTTP errors in general, fall within the 427 remit, you’ll be pleased to hear; our technical team are knowledgeable and proactive, which means they can remove barriers to Google crawlers before they become an issue; this includes these errors. By helping our clients manage their website downtime alongside our other SEO services, they stand in good stead for good rankings, making them more visible, and irresistible to users that can ultimately convert.

For all things SEO, technical and otherwise, give us a shout; we’re happy to help, always.

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About Chris Simmons

Chris is our onpage SEO Specialist at 427 Marketing, having joined the team in early 2023. He works with our content team to cover the 4 pillars of SEO; content, onpage SEO, technical SEO and offpage SEO. Prior to joining the 427 Marketing team, Chris spent almost 10 years applying his SEO and content skills across several different industries in marketing agency and inhouse roles including tool hire, auctioneering, health care within the NHS and high end luxury retail in both B2B and B2C capacities. His passion for writing, content, UX, technical and on page SEO has expanded our content offerings, helping provide reliable advice about all things SEO to 427 Marketing.

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