[gmaxwell@argonaut src]$ ./bitcoin-cli getblockstats 101
{
  "avgfee": 0,
  "avgfeerate": 0,
  "avgtxsize": 0,
  "blockhash": "00000000b69bd8e4dc60580117617a466d5c76ada85fb7b87e9baea01f9d9984",
  "feerate_percentiles": [
    0,
    0,
    0,
    0,
    0
  ],
  "height": 101,
  "ins": 0,
  "maxfee": 0,
  "maxfeerate": 0,
  "maxtxsize": 0,
  "medianfee": 0,
  "mediantime": 1231657185,
  "mediantxsize": 0,
  "minfee": 0,
  "minfeerate": 0,
  "mintxsize": 0,
  "outs": 1,
  "subsidy": 5000000000,
  "swtotal_size": 0,
  "swtotal_weight": 0,
  "swtxs": 0,
  "time": 1231661741,
  "total_out": 0,
  "total_size": 0,
  "total_weight": 0,
  "totalfee": 0,
  "txs": 1,
  "utxo_increase": 1,
  "utxo_size_inc": 117
}
[gmaxwell@argonaut src]$ ./bitcoin-cli getblockstats 100000
error code: -8
error message:
One or more of the selected stats requires -txindex enabled

Stats that require txindex should always fail if txindex isn't enabled and the stat is requested, and those stats should not be offered by default.

Also, although the help says it will accept a '1. "hash_or_height"     (string or numeric, required) The block hash or height of the target block', that doesn't seem to work regardless of how I quote it.

[gmaxwell@argonaut src]$ ./bitcoin-cli getblockstats "0000000000000000001b98c07fca289e1ca3358aeabdcca9b7f7ba704d83a3d4"
error: Error parsing JSON:0000000000000000001b98c07fca289e1ca3358aeabdcca9b7f7ba704d83a3d4



{
    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2)
        throw std::runtime_error(
            "getblockheader \"hash\" ( verbose )\n"
            "\nIf verbose is false, returns a string that is serialized, hex-encoded data for blockheader 'hash'.\n"
            "If verbose is true, returns an Object with information about blockheader <hash>.\n"
            "\nArguments:\n"
            "1. \"hash\"          (string, required) The block hash\n"
            "2. verbose           (boolean, optional, default=true) true for a json object, false for the hex-encoded data\n"
            "\nResult (for verbose = true):\n"
            "{\n"
            "  \"hash\" : \"hash\",     (string) the block hash (same as provided)\n"
            "  \"confirmations\" : n,   (numeric) The number of confirmations, or -1 if the block is not on the main chain\n"
            "  \"height\" : n,          (numeric) The block height or index\n"
            "  \"version\" : n,         (numeric) The block version\n"
            "  \"versionHex\" : \"00000000\", (string) The block version formatted in hexadecimal\n"
            "  \"merkleroot\" : \"xxxx\", (string) The merkle root\n"
            "  \"time\" : ttt,          (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"mediantime\" : ttt,    (numeric) The median block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"nonce\" : n,           (numeric) The nonce\n"
            "  \"bits\" : \"1d00ffff\", (string) The bits\n"
            "  \"difficulty\" : x.xxx,  (numeric) The difficulty\n"