Why does the sale of my BNB transaction give an error?

You have Binance as an exchange and you have indicated that Binance can settle its transaction costs in BNB. Binance gives you a significant discount in return.

As a result, Binance mutates your crypto balance on the BNB account negatively for the transaction costs. So if you do not make additional deposits, the coins that the trader has taken as a buying position are no longer on the BNB account.

The result is an error message in the trader when selling: after all, the position cannot be sold due to insufficient balance.

Solution: log in to Binance and buy enough BNB to pay the transaction costs.