HTTP 226 IM Used vs 431 Request Header Fields Too Large
HTTP 226 (IM Used) is a 2xx Success response, while 431 (Request Header Fields Too Large) is a 4xx Client Error response. 226 indicates that the server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations. In contrast, 431 means that the server refuses to process the request because an individual header field or all headers collectively are too large.
Description
The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations.
When You See It
When using delta encoding to reduce bandwidth.
How to Fix
Rarely encountered. The response uses Instance Manipulations (IM) as specified.
Description
The server refuses to process the request because an individual header field or all headers collectively are too large.
When You See It
When cookies accumulate to an excessive size, or a single header (like Authorization) is too long.
How to Fix
Reduce header sizes. Clear excessive cookies. Use shorter tokens.
Key Differences
226 is a 2xx Success response, while 431 is a 4xx Client Error response.
HTTP 226: The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations.
HTTP 431: The server refuses to process the request because an individual header field or all headers collectively are too large.
You encounter 226 when when using delta encoding to reduce bandwidth.
You encounter 431 when when cookies accumulate to an excessive size, or a single header (like Authorization) is too long.
When to Use Which
For 226 (IM Used): Rarely encountered. The response uses Instance Manipulations (IM) as specified. For 431 (Request Header Fields Too Large): Reduce header sizes. Clear excessive cookies. Use shorter tokens.