HTTP 101 Switching Protocols vs 422 Unprocessable Content
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 422 (Unprocessable Content) is a 4xx Client Error response. 101 indicates that the server understands the Upgrade header field request and indicates which protocol it is switching to. In contrast, 422 means that the server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
説明
The server understands the Upgrade header field request and indicates which protocol it is switching to.
このコードが表示される場合
When upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
解決方法
This is normal behavior during protocol upgrades. Ensure your client supports the target protocol.
説明
The server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
このコードが表示される場合
When form validation fails — correct syntax but invalid data (e.g., email format wrong, date in the past).
解決方法
Check the response body for specific validation errors and correct the input data.
主な違い
101 is a 1xx Informational response, while 422 is a 4xx Client Error response.
HTTP 101: The server understands the Upgrade header field request and indicates which protocol it is switching to.
HTTP 422: The server understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 422 when when form validation fails — correct syntax but invalid data (e.g., email format wrong, date in the past).
どちらをいつ使うか
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 422 (Unprocessable Content): Check the response body for specific validation errors and correct the input data.