hello everyone, Good evening

sorry to bother you about this issue i got from a customer. i sold a product to him for $100
i gave him wallet and he sent btc $100 and paste me txid which i saw the payment in my wallet ( Unconfirmed )

surprisingly, this guy logoff the chat and i wonder why he left so hurriedly just after i gave him the passwords to the achieved file.

i had to recheck if the payment has gotten any confirmation but surprisingly this transaction stated its INVALID with a error message at the top of the page
rechecked my wallet and i did not see the transaction again. 

below is the txid of the transaction, you can see the error message there.

https://www.blockchain.com/btc/tx/2f362caac5d3fa3a1cc586f5bdbb36bcfe6446cfc112eb1cb097d9669688204a

my wallet:  34Y9ZwTsT3H9zcnffirc2NM4XMkNmaLws6

Please. how is this possible. i really want to know this to avoid another of this.

chat screenshot
https://i.imgur.com/GLy3rhD.png