HTTP 412 Precondition Failed vs 418 I'm a Teapot
Both HTTP 412 (Precondition Failed) and 418 (I'm a Teapot) belong to the 4xx Client Error category. 412 indicates that one or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false. Meanwhile, 418 means that any attempt to brew coffee with a teapot should result in this error. An April Fools' joke from 1998 that became a beloved part of HTTP culture.
Description
One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
When You See It
When using conditional requests with ETags and the resource has changed.
How to Fix
Refresh the ETag/Last-Modified value and retry with updated preconditions.
Description
Any attempt to brew coffee with a teapot should result in this error. An April Fools' joke from 1998 that became a beloved part of HTTP culture.
When You See It
As an Easter egg on some websites, or when a server humorously refuses a request.
How to Fix
Use a coffee pot instead of a teapot. Or just enjoy the joke.
Key Differences
HTTP 412: One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
HTTP 418: Any attempt to brew coffee with a teapot should result in this error. An April Fools' joke from 1998 that became a beloved part of HTTP culture.
You encounter 412 when when using conditional requests with ETags and the resource has changed.
You encounter 418 when as an Easter egg on some websites, or when a server humorously refuses a request.
When to Use Which
For 412 (Precondition Failed): Refresh the ETag/Last-Modified value and retry with updated preconditions. For 418 (I'm a Teapot): Use a coffee pot instead of a teapot. Or just enjoy the joke.