In this blog post, we will explain what the HTTP 421 Misdirected Request Error is and how to fix it.. The HTTP 421 status code indicates that the client’s request sent to a web server is unable to be processed. This occurs because the server is not configured to handle that. It typically occurs when a server receives a request for a domain that is not authorized to respond to. This is usually with multiple domains with shared SSL certificates. We will explain a little bit more about the HTTP 421 code, its causes and how to fix it.
Fixing the HTTP 421 is straightforward, and you will need around 10 minutes to read and understand it. Let’s get started!
What is HTTP 421 Status Code?
A HTTP 421 Status Code, known as HTTP 421 Misdirected Request, is a status code that indicates that the server is not able to establish a connection with the client due to issues related to the configuration and network itself, although the server understands the request. When the client sends the request and when the server returns the HTTP 421, most probably the problem is temporary. The HTTP 421 was introduced in the HTTP/2. Such an error message can be sent back in the browser as a result of connection reuse. In such cases the server does not allow clients to reuse the connection. The HTTP 421 belongs to the HTTP 4xx status codes family. It indicates that the issue is on the client side. In the next paragraph, we will explain the causes for this status code.
What are the causes for the HTTP 421 error to appear?
In this section, we will list the possible causes for the HTTP 421 error.
Shared SSL Certificates is one of the most common reasons for this error to appear because using a single SSL certificate for multiple domains when one is intended as primary and the others as children is not recommended.
HTTP/2 and SNI Issues are also one of the reasons. Misconfigured SSL certificates or mismatched hostnames in the SNI (Server Name Identification) can trigger this error.
Incorrect Server Configuration, such as misconfigured virtual host files or not properly imported and defined SSL certificates into the Virtual host files, can cause the HTTP 421 error to occur.
Misconfigurations on the Client-Side, such as using proxies, firewalls, wrongly configured network, may also lead to the HTTP 421 status code.
Too Many connections is also one of the reasons for this error. If a client opens many simultaneous connections from the same IP address, the server may refuse to form a connection.
Connection reuse: When a single connection can be used to send multiple requests in HTTP/2 protocol from a client to a server.
How to Fix the HTTP 421 Misdirected Request Error?
In this section we will propose some possible fixes for the HTTP 421 error.
SSL Certificates: Be sure to use separate SSL certificates for each domain to avoid conflicts. If you are using a wildcard SSL certificate, make sure it is properly ordered from the certificate authority. The proper installation is also important.
Virtual Host Files: Check the virtual host file configuration and verify that the syntax is OK and there are no errors. You should pay attention in the domain name part, SSL certificate definition lines, and double-check if your web server can handle SNI for HTTPS connections. If using HTTP/2, verify that the SSL configuration is consistent across all virtual hosts.
Use Load Balancer: To verify that there are no reused requests and each request goes to the proper server. Implementing this will avoid reusing the connections across different domains.
Clear the Web Browser cache cookies, and history, or try to access the website in incognito mode or with another web browser. Sometimes old and outdated cache may cause the HTTP 421 error.
Hosting Provider: Contact the hosting provider if the error persists because sometimes the issue may be related to the hosting environment and their specific configuration on how to handle the SSL certificates on multiple domains.
Conclusion
The HTTP 421 or any HTTP 4xx status code can have a direct or indirect impact on the SEO of the website. In this case, the HTTP 421 will have an indirect impact on the SEO by impacting the user experience. The search engines like Google or Yahoo value the quality of the user experience. If the HTTP 421 error occurs too often, the user might get frustrated and leave the website, which will lower the rank, cause indexing issues, and reduce the crawl rate. That is why the website owner needs to fix this issue immediately if it occurs.
These were the basic steps to perform to fix the HTTP 421 Misdirected Request Error.
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