This is an example call for eth_getTransactionByBlockHashAndIndex.
{
"jsonrpc": "2.0",
"id": "1",
"method": "eth_getTransactionByBlockHashAndIndex",
"params": [
"",
"0x0"
]
}
{
"jsonrpc": "2.0",
"id": "1",
"error": {
"code": -32602,
"message": "data types must start with 0x"
}
}