HTTP 104 Unassigned
HTTP 104 is an unassigned status code with no official definition in the IANA HTTP status code registry or any published RFC. IANA lists it as unassigned. If you encounter a 104 response, it is generated by a non-standard or proprietary application using an undocumented code.
Quick reference
| Code | 104 |
|---|---|
| Name | Unassigned |
| Category | 1xx Informational |
| Specification | IANA Registry (Unassigned) |
| IANA status | Unassigned — no official definition |
| Cacheable | No |
| Client action | Treat as an unrecognized 1xx response and ignore it per RFC 9110. |
| In-depth guide | HTTP 104 full guide → |
What HTTP 104 means
IANA's HTTP status code registry lists 104 as unassigned — it has not been claimed by any RFC or specification. Despite this, some applications return 104 for proprietary or non-standard purposes. Without context from the specific application returning it, 104 has no defined meaning.
RFC 9110 specifies that HTTP status codes are extensible, and 1xx codes in particular are informational interim responses. Per RFC 9110, a client that receives an unrecognized 1xx status code must ignore it — 1xx responses are not final and do not represent the outcome of the request. The final response will follow.
If you encounter 104 in server logs or API responses, check the documentation for the system generating it, as it is a proprietary extension code with no standard definition.
Assigned 1xx codes
FAQ
What does HTTP 104 mean?
HTTP 104 has no official definition — IANA lists it as unassigned. If you see it, it is from a system using a non-standard code. Check that system's documentation for the specific meaning.
How should a client handle an unrecognized 1xx code?
RFC 9110 says clients must ignore unrecognized 1xx responses. They are informational and interim — the final response will still arrive on the same connection.
Could 104 be assigned in the future?
Yes. Unassigned codes can be claimed by future RFCs. If a future RFC assigns 104 to a specific meaning, the IANA registry will be updated and that assignment will become the standard definition.
Related resources
On this site: HTTP 104 — full guide · HTTP 100 Continue · HTTP 101 Switching Protocols · HTTP 103 Early Hints
Standards: IANA HTTP Status Code Registry