This blog post will explain the HTTP 412 precondition failed error, what causes it, and how to fix it. HTTP 412 is a standard status code that belongs to the 4xx client errors that indicate the client causes the issue. In the following paragraphs, we will explain how this status code differs from the others and propose several possible solutions.
What is the HTTP 412 Precondition Failed Error?
An HTTP 412 status code is a client error response message indicating that access to the target resources was denied. This code also tells us that the request methods are other than GET or HEAD when the conditions specified by the headers are not fulfilled. In other words, this status code happens when the server refuses to process the request from the client because some conditions set by the client are not met, preventing the server from completing the request./p>
The conditions, usually called ” preconditions,” are defined in the request headers. The common preconditions are If-Match and If-Unmodified-Since, which must be correct for a successful request. If the resource identifier no longer matches the version stored on the server, the server will not complete the request, and the web browser will throw an HTTP 412.
What causes the HTTP 412 Error?
As we said in the previous paragraph, the 412 status code occurs when a server is unable to process the request due to certain preconditions not being met. The following paragraphs in this section will explain the common causes in more detail.
Conditional Headers include “If-Match,” “If-None-Match,” “If-Modified-Since,” and “If-Unmodified-Since.” These headers determine the conditions that must be fulfilled correctly for the server to process the request and provide the resource. If one of these conditional headers is not met, HTTP 412 will occur.
Outdated Info is one reason the browser throws this error: the sent data does not match the server’s current version.
The outdated cache is also the reason HTTP 412 occurred. Web browsers or applications often store copies of the most frequently accessed resources, and all that is stored in the browser’s cache. When a client tries to modify a cached resource that is no longer fresh and obsolete, with mismatched pre-conditions, it may result in an HTTP 412 error.
How can the HTTP 412 Precondition Failed Error be prevented?
To prevent the Precondition error, you must be a client or a server owner. The following paragraphs will show you some client-side and server-side solutions. First, we will start with possible client-side solutions.
Clear the web browser cache, cookies, and history first. This will clear all the outdated content stored in your browser while accessing the website, which is throwing the HTTP 412 Error. Clearing the web browser cache
If your browser has any recently installed or updated extensions, disable them. If that solves the issues, enable the extensions one by one to detect which is the culprit.
From a server aspect, there are multiple possible solutions:
Verify the Precondition logic behind handling conditional requests and ensure it accurately reflects the intended behavior.
Consistent ETag Generation is one of the most essential parts for HTTP 412 never to occur. If there is an inconsistent ETag generation, it may lead to unnecessary 412 errors when clients send ETags. The ETag will not match the server’s, even though no real data modification has been done.
Refresh Timestamps: If there is a mismatch, update the request headers, verify the accuracy, and monitor the changes.
Improve the Error Handling Mechanism by clearing the error messages, including instructions or tips on how users can adjust their requests, offer links to support resources where users can find more help, etc.
How HTTP 412 Affects SEO?
The effects of this error can negatively impact a website’s SEO. It will increase the bounce rate since visitors will immediately leave the website if they receive the HTTP 412 error. The website’s search engine rating will decrease and have lower indexing. All this will lead to a poor user experience, decreased page views, and traffic loss. That’s why it is always crucial for the server owner to prevent HTTP 412 from happening.
That’s it! You have learned some basic steps for resolving the HTTP 412 Precondition Error.
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