Geth version : 1.8.3 stable
OS & Version : windows 10

{
    "config": {
        "chainId"       : 7686,
        "homesteadBlock": 0,
        "eip155Block"   : 0,
        "eip158Block"   : 0
    },
    "nonce"     : "0x0000000000000042",
    "timestamp" : "0x00",
    "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "extraData" : "0x00",
    "gasLimit"  : "0x4c4b40",
    "difficulty": "0x400000",
    "mixhash"   : "0x0000000000000000000000000000000000000000000000000000000000000000",
    "coinbase"  : "0x0000000000000000000000000000000000000000",
    "alloc": {
    }
}

ERROR[04-17|19:26:01]
########## BAD BLOCK #########
Chain config: {ChainID: 7686 Homestead: 0 DAO: <nil> DAOSupport: false EIP150: <nil> EIP155: 0 EIP158: 0 Byzantium: <nil> Constantinople: <nil> Engine: unknown}

Number: 1
Hash: 0xcc00615c7554b7c9d8813943e43216e7c4a8dcea6db6e262a8bc6c213d78733c


Error: invalid mix digest
##############################

WARN [04-17|19:26:01] Synchronisation failed, dropping peer    peer=cadcc80d87d6245a err="retrieved hash chain is invalid"