> 202 would be another
replyThen you'd return 202 on a request to delete any invalid element, which really doesn't sound right.
> 200 with some sort of response to distinguish (e.g. { changed: boolean }).
Sounds even worse, and much like APIs that returns 200 with a payload saying {error:"not found"}
> Then you'd return 202 on a request to delete any invalid element, which really doesn't sound right
replyIt depends on your use-case if you care about this or not. If you do care you will have to handle it either way somehow.
But if you want an idempotent API then a success is more appropriate IMO than an error.