What different server error codes mean for SEO

How to spot a server side SEO emergency with a list of server responses and what they mean.

When a search engine, or indeed a user, clicks a link or types a URL into the browser, a message is sent to the server, where your site lives. How the server responds is crucial to how well your site is received by search engines.

Imagine going into a store and looking for a product. If most of the shelves were empty, or most of the products were faulty, you’d probably not think very highly of that store. Google, and the other search engines, are exactly the same in terms of how they view your site. So it’s crucial that you understand the various server responses. Here’s a quick run-down.

200 is the good guy. He’s the one you want. If everything is OK, the web page exists etc, the server will return a ‘200’. This is code-speak for ‘OK’. (There is presumably a reason why human technicians couldn’t get the servers to use words like ‘OK’, ‘Not OK’ etc, rather than numbers, but I’m afraid I don’t know it. Because the more difficult it is, the more they get paid? Who knows.)

301s are what we call permanent redirects. The page you’re looking for has moved somewhere else for good. 301s make great SEO and you’ll hear me and a lot of other SEOs talk about them a lot.

301s are the most SEO-friendly form of redirection. Why? Because if you 301 page A to page B, all the love Google has for that page (we call this “link juice”) gets passed to the new page. SEOs love 301s.

302s are 301s’ ugly sister. No one likes them and they're almost always used incorrectly. (That’s not to say there would be a correct way to ‘use’ an ugly sister. I’m terrible with metaphors).

Once upon a time, they were the default redirection tool for a number of content management systems (so they hang around the web like a bad smell) but their use is very limited; if you want to temporarily move some pages around your site. Eg, if you have a promotion on, you’d want anyone who clicks on a given product page to see the offer, but you perhaps wouldn’t want to bother fiddling around with the existing page. You would then redirect that web address to your more promotional one. Google won’t pass on any juice because it knows it’s temporary. It’s really for your users’ benefit.

401s are for paywalls and any content that users need to log in to see. Google, and other search engines and crawlers, can’t access this content (in fact, if you can’t get there just by using a mouse, it’s inaccessible to Google). Make sure that all content behind a wall has a reason to be there. If not, put it outside.

404 responses are for when the server can’t find a given page, perhaps because the webmaster has deliberately pulled it, or perhaps moved a page and forgotten to redirect it. Or maybe the user typed in the web address wrong. Whatever the reason, 404s are more common than you can ever imagine. A number of well-known brands have their own bespoke ones. Some are pretty cool, maybe something like this would be right for you?

example of 404 error page

410s are useful for when you’ve deliberately pulled a page. Most of the time when that happens, you would just redirect it to another page, or back to the home page. But if you know a given page has lots of links from a bad neighborhood, it’s worth 410'ing those pages to get them out of your system. Like a septic leg, you don’t want it infecting everything else, so you amputate. In practice, the only real difference between this and a 404 is that Google will remove the affected page a little quicker with a 410.

500 is a generic response. It doesn’t tell us anything, so I’m not going to either. Sorry.

503 means that something is wrong – the page is down for some reason. If you get lots of these, you need to sort something out quick.

So those are the main ones. How many server problems does your site have? 

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