If you recently switched from Google Messages back to Samsung Messages, your number might still be "active" on Google's end, causing a conflict. Go to the official Google RCS de-registration page .
Before fixing the problem, you need to understand the backend. Samsung Messages uses RCS (Rich Communication Services), not traditional SMS. Unlike iMessage (which uses Apple’s servers), Samsung—in most regions—relies on platform or your Carrier’s own RCS backend (e.g., T-Mobile, Verizon, AT&T). samsung messages chat registration failed fixed
If you have tried all the above and the error persists, the issue may be If you recently switched from Google Messages back