Nonexisting sender account

I am trying to make use a new node with existing mainnet account. It returns Nonexisting sender account.

My node is running on v6 and above.

Node Ip:
Node Port: 20000

What could be the reason for this?

The most likely reason is that your node is not yet caught up with the head of the chain.

The solution is to wait until it is.

How long does it take to catch up with the head of the chain?

On mainnet a few days, it depends a bit on the speed of your machine, especially disk.