HTTP 101 Switching Protocols vs 415 Unsupported Media Type
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 415 (Unsupported Media Type) 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, 415 means that the server refuses to accept the request because the Content-Type is not supported.
Description
The server understands the Upgrade header field request and indicates which protocol it is switching to.
When You See It
When upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
How to Fix
This is normal behavior during protocol upgrades. Ensure your client supports the target protocol.
Description
The server refuses to accept the request because the Content-Type is not supported.
When You See It
When sending JSON to an endpoint that only accepts XML, or missing the Content-Type header.
How to Fix
Set the correct Content-Type header matching the data format you're sending.
Key Differences
101 is a 1xx Informational response, while 415 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 415: The server refuses to accept the request because the Content-Type is not supported.
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 415 when when sending JSON to an endpoint that only accepts XML, or missing the Content-Type header.
When to Use Which
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 415 (Unsupported Media Type): Set the correct Content-Type header matching the data format you're sending.