> For the complete documentation index, see [llms.txt](https://help.coinpocket.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.coinpocket.io/wallet-faq/btc-wallet/why-does-my-usdt-prompt-an-address-error-when-i-want-to-transfer-to-a-bitcoin-address.md).

# Why does my usdt prompt an address error when I want to transfer to a bitcoin address?

The bitcoin-based USDT (issued under the Omni protocol) and ethereum-based USDT (issued under the erc-20 protocol) cannot transfer to each other.

When transferring USDT, you can tell whether the USDTs are based on the same protocol by their address starting numbers: the USDT issued under Omni protocol starts with "1", and the USDT issued under erc-20 protocol starts with "0x".