When you see the error 'Preview_Insufficient_funds' in your Coinbase trading bot, it means that you are trying to place an order using more of the quote currency than is currently available in your Coinbase account. Coinbase rejects the order before it is placed.
Cause
Your available quote currency balance is lower than the amount needed to place the order.
How to fix it
There are two ways to resolve this:
Top up your balance — deposit more of the quote currency into your Coinbase account so there are enough funds to cover the order.
Wait for an open position to be sold — once Cryptohopper sells an existing position, the quote currency is returned to your balance and new orders can be placed again.
How to prevent this error
You can prevent this error by using a slightly smaller amount of the quote currency for your buy orders. Keep in mind that your order amount must still meet the minimum order amount required by Coinbase. If your amount is set too low, your orders may be rejected for a different reason.
Example of the error
Example of the error in the trading bot output:
05/21/2024 6:41:56 PM ERROR Error placing buy order, data: {"error":"PREVIEW_INSUFFICIENT_FUND: Insufficient balance in source account","orderNumber":""}