when i run my code i have this error "process 1 exited without calling finalize" what is the cause? although I put a barrier before the end of my code

MPI_Init(&argc, &argv);

MPI_Comm_rank(MPI_COMM_WORLD, &rang_proc);

MPI_Comm_size(MPI_COMM_WORLD, &nbr_proc);

//parallel code 

MPI_Barrier(MPI_COMM_WORLD);

MPI_Finalize();