4×× CLIENT ERROR
The target resource is no longer available at the origin server and that this condition is likely to be permanent.
If the origin server does not know, or has no facility to determine, whether or not the condition is permanent, the status code 404 Not Found ought to be used instead.
The 410 response is primarily intended to assist the task of web maintenance by notifying the recipient that the resource is intentionally unavailable and that the server owners desire that remote links to that resource be removed. Such an event is common for limited-time, promotional services and for resources belonging to individuals no longer associated with the origin server’s site. It is not necessary to mark all permanently unavailable resources as “gone” or to keep the mark for any length of time — that is left to the discretion of the server owner.
A 410 response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls.
Calculating Heuristic Freshness RFC7234 Section 4.2.2
410 GONE Source: RFC7231 Section 6.5.9
410 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