HTTP 101 Switching Protocols vs 304 Not Modified
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 304 (Not Modified) is a 3xx Redirection response. 101 indicates that the server understands the Upgrade header field request and indicates which protocol it is switching to. In contrast, 304 means that the resource has not been modified since the last request. The client can use its cached copy.
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 resource has not been modified since the last request. The client can use its cached copy.
このコードが表示される場合
When the browser cache is still valid (If-None-Match / If-Modified-Since headers match).
解決方法
No fix needed. This saves bandwidth by confirming the cached version is still current.
主な違い
101 is a 1xx Informational response, while 304 is a 3xx Redirection response.
HTTP 101: The server understands the Upgrade header field request and indicates which protocol it is switching to.
HTTP 304: The resource has not been modified since the last request. The client can use its cached copy.
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 304 when when the browser cache is still valid (If-None-Match / If-Modified-Since headers match).
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 304 (Not Modified): No fix needed. This saves bandwidth by confirming the cached version is still current.