Zcash-cli z_getbalance error code -28

Hi
I’ve installed Zcash on Ubuntu. I try to do sample operation for example getbalance. But server throw error.

root@1d45a51f1530:/home/zcash# ./src/zcash-cli getbalance “t1apTvGVJKMjaK9UdazAxSabm6DMPhQdkqM”
error code: -28
error message:
Loading block index…
[3]+ Exit 1 ./src/zcashd > /dev/null 2> /dev/null
root@1d45a51f1530:/home/zcash#

This is my config file:
testnet=0
addnode=mainnet.z.cash
rpcuser=username
rpcpassword=password
gen=1

What is the reason?

As the error message says, your node is still starting up and loading the block index. You can’t make any RPC calls until the node has started.

Ok, thanks, I waited a moment after start node and now it works.