is used to carry additional information about the status or transformation of a message that might not be reflected in the message.
Quick facts
Description
is used to carry additional information about the status or transformation of a message that might not be reflected in the message.
Syntax
Warning: 110 - "Response is stale"
Related status codes
Frequently asked questions
is used to carry additional information about the status or transformation of a message that might not be reflected in the message.
It is classified as a general header and can appear in requests or responses depending on context.
Sources & standards
Updated 2026-08-18
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