{"id":80633,"date":"2025-11-03T16:37:36","date_gmt":"2025-11-03T21:37:36","guid":{"rendered":"https:\/\/www.inmotionhosting.com\/blog\/?p=80633"},"modified":"2026-02-02T14:01:36","modified_gmt":"2026-02-02T19:01:36","slug":"400-series-error-codes-guide","status":"publish","type":"post","link":"https:\/\/www.inmotionhosting.com\/blog\/400-series-error-codes-guide\/","title":{"rendered":"400 Series Error Codes: What They Mean, Why They Matter, and How You Fix Them"},"content":{"rendered":"\n
\"400<\/figure>\n\n\n

400 series error codes are client-side issues that can hurt SEO, user trust, and overall site performance if left unmanaged. This guide explains the most common codes, along with the less frequent ones you may encounter. You\u2019ll learn how to troubleshoot errors, create branded 404 pages, and use WordPress tools like automatic redirects to catch broken links before they impact visitors. By combining prevention with smart fixes, you ensure a faster, more reliable experience for your audience. <\/p><\/div>\n\n\n

When your website throws a 4xx error<\/a>, visitors see a wall instead of your content. These 400 series error codes are client-side HTTP responses that signal something went wrong with the request, not necessarily your server. <\/p>\n\n\n\n

But here\u2019s the catch: your users (and search engines) still blame the experience on you. <\/p>\n\n\n\n

In this guide, you\u2019ll learn what each major 4xx code means, how to diagnose the root cause, and how to fix and prevent them, especially in WordPress. You\u2019ll also get practical steps to set up smart, automatic redirects for 404s so you protect rankings and conversions without babysitting links.<\/p>\n\n\n\n

We\u2019ll cover the familiar codes (400, 401, 402, 403, 404), then touch on less common but important ones. Along the way, you\u2019ll see real-world WordPress tactics, including when to use plugins, what not to do (hint: don\u2019t dump 404s to your homepage), and how to structure helpful 404 pages that keep visitors moving.<\/p>\n\n\n\n

Before diving into the individual codes, it\u2019s helpful to understand how the entire 400 series works. These error messages share common traits but also have unique triggers that can confuse both users and site owners. By starting with the big picture, you\u2019ll see how each status code fits into the broader category of client-side issues.<\/p>\n\n\n\n

What Are 400 Series Error Codes?<\/h2>\n\n\n\n

HTTP status codes help browsers and APIs communicate outcomes: success, redirects, client errors, and server errors. 4xx codes are the \u201cclient error\u201d class. They usually mean the request was malformed, missing permissions, or pointed at something that doesn\u2019t exist.<\/p>\n\n\n\n