HTTP 101 Switching Protocols vs 404 Not Found
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 404 (Not Found) 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, 404 means that the server cannot find the requested resource. The URL may be wrong, the resource may have been deleted, or it may never have existed.
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 cannot find the requested resource. The URL may be wrong, the resource may have been deleted, or it may never have existed.
When You See It
When a URL is mistyped, a page has been deleted, or an API endpoint doesn't exist.
How to Fix
Verify the URL is correct. Check for typos, case sensitivity, and trailing slashes.
Key Differences
101 is a 1xx Informational response, while 404 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 404: The server cannot find the requested resource. The URL may be wrong, the resource may have been deleted, or it may never have existed.
You encounter 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 404 when when a URL is mistyped, a page has been deleted, or an API endpoint doesn't exist.
When to Use Which
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 404 (Not Found): Verify the URL is correct. Check for typos, case sensitivity, and trailing slashes.