102 Processing

HTTP 102 Processing is a WebDAV interim response used to prevent a client from assuming a connection has died while the server works through a request that takes longer than a typical HTTP round trip. Operations like COPY or MOVE across many resources, or a PROPFIND against a huge collection, can take longer than a client's default timeout to fully process. Rather than leaving the connection silent, the server periodically sends 102 to indicate progress is being made, and the client keeps waiting for the eventual final status.

Because 102 carries no body and no final semantics, a client cannot treat it as success or failure, it simply resets whatever timeout it was tracking. In practice this status is rare outside dedicated WebDAV servers, since most modern APIs use asynchronous patterns such as 202 Accepted with a polling location instead of holding a connection open. Generic HTTP libraries that never expect 1xx interim responses beyond 100 sometimes mishandle 102, either by hanging or by misreporting it as the final response.

Where it does appear, it is almost always emitted by WebDAV-capable file servers, source control front ends, or CMS backends handling bulk file operations. Load balancers and CDNs that buffer responses or enforce their own idle timeouts can break the mechanism entirely, since they may close the connection before the informational responses reach the client. Teams building on top of WebDAV should test behavior through any proxy layer explicitly rather than assuming 102 will pass through untouched.