424 Failed Dependency
Meaning
The request failed because it depended on another operation that failed. This is used in contexts like WebDAV where an earlier request (e.g., a PROPPATCH) failed, causing the current request to fail as well.
When to Use
When an operation cannot succeed because a previous action in the context failed. Often used in multi-step or batch processing scenarios to indicate that the chain of operations was broken by a failure earlier.
Example
If a client attempts a WebDAV PROPPATCH on a resource after a previous related operation failed (like locking the resource), the server might return 424 Failed Dependency to indicate it can't proceed due to that earlier failure.
When Not to Use
Do not use in single-operation requests that aren't dependent on prior requests. This is typically relevant in multi-part or transaction-like requests where one part failing affects another.
Source
RFC 4918 (WebDAV)