hods/HEAD) .

If the server _does_ recognize the method, but intentionally does not support
it, the appropriate response is [ ` 405 Method Not Allowed ` ](/en-
US/docs/Web/HTTP/Status/405) .

**Note:**

  * A 501 error is not something you can fix, but requires a fix by the web server you are trying to access. 
  * A 501 response is cacheable by default; that is, unless caching headers instruct otherwise. 

##  Status

http

    
    
    501 Not Implemented
    

##  Specifications

Specification  
---  
[ HTTP Semantics  
#  status.501  ](https://www.rfc-editor.org/rfc/rfc9110#status.501)  
  
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  *[
                
                 Non-standard
                
               ]: Non-standard. Check cross-browser support before using.
  *[
                
                 Deprecated
                
               ]: Deprecated. Not fo