When trying to run split chunk command with boundaries or with sh.splitFind() command and there are no documents in the collection, the error received back is:
> sh.splitFind(ns, {_id:1}) { "cause" : { }, "ok" : 0, "errmsg" : "split failed" }
The logs for mongos says:
m30999| 2014-02-07T14:57:49.007-0500 [conn3] splitting chunk [{ _id: 5764607523034234880 },{ _id: 6148914691236517204 }) in collection test.clicks2014w5 on shard shard0002 m30002| 2014-02-07T14:57:49.010-0500 [conn4] command admin.$cmd command: { splitVector: "test.clicks2014w5", keyPattern: { _id: "hashed" }, min: { _id: 5764607523034234880 }, max: { _id: 6148914691236517204 }, force: true } ntoreturn:1 keyUpdates:0 numYields:0 locks(micros) r:100 reslen:53 0ms m30999| 2014-02-07T14:57:49.011-0500 [conn3] want to split chunk, but can't find split point chunk ns: test.clicks2014w5, shard: shard0002:localhost:30002, lastmod: 3|85||000000000000000000000000, min: { _id: 5764607523034234880 }, max: { _id: 6148914691236517204 } got: <empty>
because field is not being populated, making it more harder to figure out why the split failed.