[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() != 0)
        throw std::runtime_error(
            "getblockchaininfo\n"
            "Returns an object containing various state info regarding blockchain processing.\n"
            "\nResult:\n"
            "{\n"
            "  \"chain\": \"xxxx\",              (string) current network name as defined in BIP70 (main, test, regtest)\n"
            "  \"blocks\": xxxxxx,             (numeric) the current number of blocks processed in the server\n"
            "  \"headers\": xxxxxx,            (numeric) the current number of headers we have validated\n"
            "  \"bestblockhash\": \"...\",       (string) the hash of the currently best block\n"
            "  \"difficulty\": xxxxxx,         (numeric) the current difficulty\n"
            "  \"mediantime\": xxxxxx,         (numeric) median time for the current best block\n"
            "  \"verificationprogress\": xxxx, (numeric) estimate of verification progress [0..1]\n"
            "  \"initialblockdownload\": xxxx, (bool) (debug information) estimate of whether this node is in Initial Block Download mode.\n"
            "  \"chainwork\": \"xxxx\"           (string) total amount of work in active chain, in hexadecimal\n"
            "  \"size_on_disk\": xxxxxx,       (numeric) the estimated size of the block and undo files on disk\n"
            "  \"pruned\": xx,                 (boolean) if the blocks are subject to pruning\n"
            "  \"pruneheight\": xxxxxx,        (numeric) lowest-height complete block stored (only present if pruning is enabled)\n"
            "  \"automatic_pruning\": xx,      (boolean) whether automatic pruning is enabled (only present if pruning is enabled)\n"
            "  \"prune_target_size\": xxxxxx,  (numeric) the target size used by pruning (only present if automatic pruning is enabled)\n"
            "  \"softforks\": [                (array) status of softforks in progress\n"
            "     {\n"
            "        \"id\": \"xxxx\",           (string) name of softfork\n"
            "        \"version\": xx,          (numeric) block version\n"
            "        \"reject\": {             (object) progress toward rejecting pre-softfork blocks\n"
            "           \"status\": xx,        (boolean) true if threshold reached\n"
            "        },\n"
            "     }, ...\n"
            "  ],\n"