Porting from 1.20.1 to 1.21.1 from 2024.4 to newest version

So, If I want to, and port my mod It works normally in Mcreator 2024.4 1.20.1 and 21, but when I open it in 2025.3 and in 1.21.1, it has errors, but when I try to fix it it doesnt work either, like I recode the procedure and "fix" it, and I rebuild its still not fixed and shows that failed to load or show in workspace to press