HTTP 301 Moved Permanently vs 501 Not Implemented
HTTP 301 (Moved Permanently) is a 3xx Redirection response, while 501 (Not Implemented) is a 5xx Server Error response. 301 indicates that the resource has been permanently moved to a new URL. All future requests should use the new URL. Search engines will transfer link equity to the new URL. In contrast, 501 means that the server does not support the functionality required to fulfill the request. The server either does not recognize the request method or lacks the ability to fulfill it.
Description
The resource has been permanently moved to a new URL. All future requests should use the new URL. Search engines will transfer link equity to the new URL.
When You See It
After domain migrations, URL restructuring, or when consolidating duplicate URLs.
How to Fix
Update links and bookmarks to the new URL in the Location header. For SEO, this is the preferred redirect for permanent moves.
Description
The server does not support the functionality required to fulfill the request. The server either does not recognize the request method or lacks the ability to fulfill it.
When You See It
When using an HTTP method (like PATCH) that the server doesn't support.
How to Fix
Use a different HTTP method that the server supports. Check server documentation.
Key Differences
301 is a 3xx Redirection response, while 501 is a 5xx Server Error response.
HTTP 301: The resource has been permanently moved to a new URL. All future requests should use the new URL. Search engines will transfer link equity to the new URL.
HTTP 501: The server does not support the functionality required to fulfill the request. The server either does not recognize the request method or lacks the ability to fulfill it.
You encounter 301 when after domain migrations, URL restructuring, or when consolidating duplicate URLs.
You encounter 501 when when using an HTTP method (like PATCH) that the server doesn't support.
When to Use Which
For 301 (Moved Permanently): Update links and bookmarks to the new URL in the Location header. For SEO, this is the preferred redirect for permanent moves. For 501 (Not Implemented): Use a different HTTP method that the server supports. Check server documentation.