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A 409 response code tells you that a request could not be completed because of a conflict with the state of the target resource. Typically, when a 409 response code occurs, the user can resolve the conflict by merging changes or modifying the existing version of the resource.
When things are working properly, the server will generate a payload to help users recognize why the conflict is occurring. This information will be available on the back end, but should not be visible to front-end users of a website.
409 codes typically occur in response to PUT requests; if a third party changes the same resource you’re attempting to modify with your PUT request before the request is completed, a 409 response code may occur.
A 409 conflict error is an incredibly useful error, though it can be tedious; without a 409 conflict, you may end up overwriting other people’s edits to the requested resource. Versioning allows us to quickly detect conflicts and give you the chance to resolve them, ensuring that everyone’s edits to a resource can be checked and merged or changed before being modified.
Paul, a blogger, is making edits to a blog he wrote. Unbeknownst to him, Aliza, his editor, is making edits to that very same blog. Aliza submits her edits while Paul is still working on the blog. When Paul submits his blog post, the system detects a conflict; the version of the blog that Paul is trying to modify is no longer available since the new version that Aliza edited has already been submitted.
Paul gets a message that his changes cannot be made because someone else has edited the blog. The message asks him to refresh the page and review the new version before trying again
The team’s developer sees a 409 code in the server logs. Here’s what the entry might look like:
2024-10-16 15:12:45 PUT /blog/123 HTTP/1.1 Response: 409 Conflict Client IP: 192.168.1.101 Resource: /blog/123 Error: Conflict detected. Resource /blog/123 was modified by another process. Client provided ETag: "abcd1234", current version: "efgh5678" Request Data: { "name": "Paul", "email": "paul@example.com" }
The developer realizes that the CMS that the team is using doesn’t allow them to merge their edits in real-time; he starts working on a solution to solve the problem.
Depending on the language you’re using, you’ll use different codes to tell your server what to do in response to 409 status codes. For reference, here’s the code used to refer to 409s in some of the most common languages:
Ruby on Rails:
Go:
Symfony (PHP):
Python 2:
Python 3+:
.NET (C#):
HttpStatusCode.Conflict
Rust:
Java:
Apache HttpComponents:
Angular (TypeScript):
Node.js (JavaScript):
Django (Python):
Flask (Python):
Spring (Java):
Laravel (PHP):
There are three steps to take in order to fix any 409 status code:
The 409 HTTP status code and the 412 HTTP status code share many similarities; both often occur when you attempt to modify the same resource that someone else has recently modified.
Unlike 409 status codes, 412 status codes occur in response to preconditions; the code is 412 Precondition Failed (as opposed to 409 Conflict). For resources that are frequently modified, using If-Match headers is best practice; a 412 conflict will occur if the versions do not match.
412 HTTP status codes can also occur when If-None-Match preconditions fail, but these errors typically occur in very different circumstances than 409 Conflict errors.
There are a few steps you can take to minimize the impacts and reduce the rate of 409 codes:
A requested resource can’t be modified when the server responds with a 409 Conflict error message. This can slow down the rate at which resources are updated. Realistically, 409 response codes are typically only seen by the people who are working on a website; normal users should almost never see a 409 response code (and with best practices, they’ll only see a user-friendly message).
This means the direct impact of 409 response codes on SEO is minimal unless a problem leads to users continually seeing 409 codes. Unfortunately, 409 codes can lead to missing or inaccurate content, broken links, missing images, and more. These problems impact user experience and thus SEO.
Fortunately, search engines like Google can still crawl and index websites even when 409 errors occur. Monitoring 409 errors to ensure that there are no systemic issues, and following best practices to ensure resources are updated efficiently, are the keys to minimizing the impact 409 errors can have on user experience.
Our SEO agency can help you optimize your site; reducing the number of technical errors on your website is one of our specialties. Contact us today for a free consultation!
Jacob Kettner is the owner and CEO of First Rank Inc., a digital marketing agency based in Winnipeg, Manitoba. He currently sits on Manitoba Chamber of Commerce Small Business Advisor Council which assists people grow their small businesses in Manitoba.
The purpose of First Rank is to help businesses generate leads from their websites. We put a focus on SEO, because we believe it is one of the most cost effective and highest converting forms of traffic generation, however traffic alone is not enough on its own to grow your business. SEO should be combined with conversion optimization, email marketing and retargeting to maximize the ROI of your advertising dollars.
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