What Is a 501 Status Code?
The server does not support the functionality required to fulfill the request.
This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource.
A 501 response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls1.
501 CODE REFERENCES
Rails HTTP Status Symbol
Go HTTP Status Constant
Symfony HTTP Status Constant
Python2 HTTP Status Constant
Python3+ HTTP Status Constant
Python3.5+ HTTP Status Constant
HttpComponents Core org.apache.hc.core5.http.HttpStatus.SC_NOT_IMPLEMENTED
501 status code example
Here is an example of a request and response that could result in a 501 status code:
GET https://example.com/unsupported-feature HTTP/1.1
HTTP/1.1 501 Not Implemented
Date: Wed, 16 Mar 2023 12:00:00 GMT
This feature is not supported.
In this example, the client is sending a GET request to access a resource at
https://example.com/unsupported-feature. However, the requested feature is not supported by the server.
The server responds with a 501 Not Implemented status code, which indicates that the server does not support the requested feature. The response also includes a message body with a plain text message that provides additional information about the error.
The server also includes several headers in the response, such as
Content-Length, which provide additional information about the response.
How to fix a 501 status code
To fix a 501 error, you can take the following steps:
- Check if the server supports the requested feature: Verify that the server actually supports the feature or functionality that the client is requesting. If the server does not support the requested feature, you can try using an alternative method or feature that is supported by the server.
- Upgrade the server: If the server is outdated or not configured correctly, it may not support the requested feature. In this case, you can upgrade the server to a newer version or configure it correctly to support the feature.
- Configure the server: Make sure that the server is configured correctly to handle the requested feature. This may involve adjusting server settings, installing necessary software or plugins, or making other configuration changes.
- Check the client request: Verify that the client is making the request correctly and using a method that is supported by the server. If the client is using an unsupported method or protocol, you can try using an alternative method or protocol that is supported by the server.
- Provide a meaningful error message: If the requested feature cannot be supported, provide a meaningful error message to the client. This can help the client understand the issue and take appropriate action.
It’s important to note that fixing a 501 error may involve changes to both the client and the server. If you’re unsure about how to fix a 501 error, consult the documentation for your server and/or application, or contact your web hosting provider or IT department for assistance.
Do 501 status codes affect search engine optimization (SEO)?
Yes, 501 errors can impact SEO. If search engine crawlers encounter 501 errors when trying to access pages or resources on a website, it can affect how the search engine indexes and ranks the site in search results.
How do 501 status codes affect SEO?
When a search engine encounters a 501 error, it may assume that the website is not functioning correctly and may lower the site’s ranking in search results. This is because search engines prioritize sites that are functional, accessible, and reliable, and a site that frequently returns 501 errors may be seen as less reliable.
Additionally, if search engines encounter many 501 errors on a site, they may reduce the frequency at which they crawl the site, which can result in slower indexing and ranking updates.
How to prevent 501 errors from hurting your SEO
To prevent 501 errors from impacting SEO, it’s important to monitor the site for errors and fix them as quickly as possible. You can use various online tools to check for 501 errors, such as Google Search Console or third-party SEO auditing tools. Once you have identified 501 errors, you can work to fix them by following the steps outlined in my previous response.
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