100 Continue
The server received the request headers; send the body.
What it means
A client that sent Expect: 100-continue asked permission before uploading a large body. The server agrees to read it.
What your client should do
Most HTTP libraries handle this automatically. Continue sending the request body.
Should you retry?
No. Repeating the same request will give the same result.
Defined in RFC 9110. All status codes and headers