oracle database memory upgrade error

when I tried to increase the sga_max_size and sga_target and got  the below error.


ISSUE:

alter system set SGA_MAX_SIZE=12288M scope=spfile;

 alter system set SGA_TARGET=12G scope=spfile;


SQL> startup pfile='initOra1.ora' mount;
ORA-00844: Parameter not taking MEMORY_TARGET into account
ORA-00851: SGA_MAX_SIZE 12884901888 cannot be set to more than MEMORY_TARGET 9663676416.
ORA-01078: failure in processing system parameters

Cause:
when I checked the parameter file and it contains AMM parameter enabled.

Solution:
remove  or comment the memory_target from the parameter file and startup with pfile  with sga_max_size & sga_target.