Hypertext Transfer Protocol (HTTP) Problem Types

Created
2023-05-02
Last Updated
2026-06-26
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Registry Included Below

HTTP Problem Types

Registration Procedure(s)
Specification Required
Expert(s)
Mark Nottingham, Sanjay Dalal
Reference
[RFC9457]
Note
New problem types and changes to existing ones can be requested using 
the [registration request interface] or the [HTTPAPI mailing list].
Available Formats

CSV
Type URI Title Recommended HTTP Status Code Reference
about:blank See HTTP Status Code N/A [RFC9457]
https://iana.org/assignments/http-problem-types#date Date Not Acceptable 400 [RFC9458, Section 6.5.2]
https://iana.org/assignments/http-problem-types#ohttp-key Oblivious HTTP key configuration not acceptable 400 [RFC9458, Section 5.3]
https://iana.org/assignments/http-problem-types#digest-unsupported-algorithms Unsupported Hashing Algorithms 400 [RFC-ietf-httpapi-digest-fields-problem-types-06, Section 3.1]
https://iana.org/assignments/http-problem-types#digest-invalid-values Invalid Digest Values 400 [RFC-ietf-httpapi-digest-fields-problem-types-06, Section 3.2]
https://iana.org/assignments/http-problem-types#digest-mismatched-values Mismatched Digest Values 400 [RFC-ietf-httpapi-digest-fields-problem-types-06, Section 3.3]