Even with the correct twrp3021smt560tar full file, issues can occur.
Create a full image backup of your current system.
You forgot to enable "OEM Unlock" in Developer Options before flashing. Fix: Reboot to stock ROM (you may need to re-flash stock firmware via Odin first), enable OEM Unlock, wait 7 days (Samsung’s RMM lock on older devices), then reflash TWRP.
Even with the correct twrp3021smt560tar full file, issues can occur.
Create a full image backup of your current system.
You forgot to enable "OEM Unlock" in Developer Options before flashing. Fix: Reboot to stock ROM (you may need to re-flash stock firmware via Odin first), enable OEM Unlock, wait 7 days (Samsung’s RMM lock on older devices), then reflash TWRP.