What common mistake do developers make with Remember me, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Remember me, why does the mistake cause problems, and what is the safer approach? One recurring problem with remember me is applying it without understanding the boundary it protects. Logging a user in successfully but failing to regenerate the session identifier as part of a secure session-authentication workflow. In addition, Persistent login options use longer-lived client state while still requiring careful security handling. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.