The "invalid address" error occurs when the address you try to send to does not match the address type of your wallet. For example, if you are using a Testnet wallet and try to send to a Bitcoin wallet. Address Prefixes In order to resolve this error, make sure you are entering an address that matches the network of your wallet. Bitcoin wallets can send to addresses with the prefix 1, 3, or bc1. Testnet wallets can send to addresses with the prefix m, 2, or tb1.