[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



{
    return "    \"size\" : n,             (numeric) virtual transaction size as defined in BIP 141. This is different from actual serialized size for witness transactions as witness data is discounted.\n"
           "    \"fee\" : n,              (numeric) transaction fee in " + CURRENCY_UNIT + " (DEPRECATED)\n"
           "    \"modifiedfee\" : n,      (numeric) transaction fee with fee deltas used for mining priority (DEPRECATED)\n"
           "    \"time\" : n,             (numeric) local time transaction entered pool in seconds since 1 Jan 1970 GMT\n"
           "    \"height\" : n,           (numeric) block height when transaction entered pool\n"
           "    \"descendantcount\" : n,  (numeric) number of in-mempool descendant transactions (including this one)\n"
           "    \"descendantsize\" : n,   (numeric) virtual transaction size of in-mempool descendants (including this one)\n"
           "    \"descendantfees\" : n,   (numeric) modified fees (see above) of in-mempool descendants (including this one) (DEPRECATED)\n"
           "    \"ancestorcount\" : n,    (numeric) number of in-mempool ancestor transactions (including this one)\n"
           "    \"ancestorsize\" : n,     (numeric) virtual transaction size of in-mempool ancestors (including this one)\n"
           "    \"ancestorfees\" : n,     (numeric) modified fees (see above) of in-mempool ancestors (including this one) (DEPRECATED)\n"
           "    \"wtxid\" : hash,         (string) hash of serialized transaction, including witness data\n"
           "    \"fees\" : {\n"
           "        \"base\" : n,         (numeric) transaction fee in " + CURRENCY_UNIT + "\n"
           "        \"modified\" : n,     (numeric) transaction fee with fee deltas used for mining priority in " + CURRENCY_UNIT + "\n"
           "        \"ancestor\" : n,     (numeric) modified fees (see above) of in-mempool ancestors (including this one) in " + CURRENCY_UNIT + "\n"
           "        \"descendant\" : n,   (numeric) modified fees (see above) of in-mempool descendants (including this one) in " + CURRENCY_UNIT + "\n"
           "    }\n"