What do various server error messages mean?

You might hit the dreaded Error page, or when checking your site links and pages, you may run into various three-digit codes that let you know the status of the page. This could indicate health issues with certain pages. We're going to try to demystify these codes with explanations about what they mean and good suggestions on what to do with them.

The Pagely Error

Hackers will use error messages to discover things about the server environment and potential loopholes. To limit the effect of this, we cover a lot of errors with a generic "Pagely" error. This could be anything, so file a detailed report with Support if you see it. We'll be able to look into the logs and fix it up. Most commonly, it's a theme or plugin trying to do something stupid.

The 200

This means everything is perfectly fine. This is what we want!

The 404

The most common 400 error. A 404 means a page not found, a broken link. It's so common that  we've dedicated a whole page to it.

The 301/302

301 and 302 are both redirects -- if you visit this URL, you'll be taken to another page. 301 means it's a permanent redirect, and the original content is never coming back. 302 means it is a temporary redirect, and the bot should check back soon for an update. 

The later is more commonly used for maintenance modes and affiliate masking, while 301s are used to move people and bots to updated URLs.

The Rest

These error messages are less common:

401 - Unauthorised The viewer needs a password or similar to access the page. SEO Implication: Search engines won't submit a username and password for entry so it won't show up in the search results. 

403 - Forbidden No access is allowed. This is common for admin pages and scripts, so don't worry unless it's on a page that should be visible.

410 - Gone This is what we should return instead of a 404 when the page is completely gone forever. Removing a product or a blog post forever? Return this.

500 - Generic Error Something went so badly wrong that we couldn't even return a 404. If this happens, contact Support.

503 - Service Unavailable For some reason one of the technologies that your website runs on was unavailable. We should see very, very few of these on Performance Foundry servers. If you see them, contact Support.

The Search Engine Implications

Moz has a great write-up on  when and why to care about these codes from an SEO perspective, but remember that it's natural to see a variety of response codes on your site, and not to worry too much about them unless you're seeing strange thing in the wrong places.