HTTP 405 Method Not Allowed vs 501 Not Implemented
HTTP 405 (Method Not Allowed) is a 4xx Client Error response, while 501 (Not Implemented) is a 5xx Server Error response. 405 indicates that the HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods. 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 HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods.
When You See It
When sending POST to a read-only endpoint, or DELETE to a non-deletable resource.
How to Fix
Check the Allow response header for supported methods. Use the correct HTTP method.
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
405 is a 4xx Client Error response, while 501 is a 5xx Server Error response.
HTTP 405: The HTTP method is not allowed for the requested resource. The response includes an Allow header listing valid methods.
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 405 when when sending POST to a read-only endpoint, or DELETE to a non-deletable resource.
You encounter 501 when when using an HTTP method (like PATCH) that the server doesn't support.
When to Use Which
For 405 (Method Not Allowed): Check the Allow response header for supported methods. Use the correct HTTP method. For 501 (Not Implemented): Use a different HTTP method that the server supports. Check server documentation.