102 Processing
Meaning
Indicates that the server has received and is processing the request, but no response is available yet.
When to Use
When a request (such as a WebDAV request) involves complex operations and will take long to complete.
Example
A WebDAV PROPPATCH request triggers a 102 Processing to prevent the client from timing out while the server works.
When Not to Use
Do not use for quick operations; only for lengthy requests. Note: This status code is deprecated and not used in HTTP/1.1 clients.
Source
RFC 2518 (WebDAV)