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.
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 understands the content type and syntax, but was unable to process the contained instructions. Common in API validation errors.
When You See It
When form validation fails — correct syntax but invalid data (e.g., email format wrong, date in the past).
How to Fix
Check the response body for specific validation errors and correct the input data.
Key Differences
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).
When to Use Which
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.