ORA-32001: write to SPFILE requested but no SPFILE is in use

When trying to change the value of  parameters db_cache_size to 2G getting below error.

alter system set db_cache_size=2G scope=spfile;
*
ERROR at line 1:
ORA-32001: write to SPFILE requested but no SPFILE is in use

Cause :Not able to change the value of db_cache_size parameter ,because the instance is running
with Memory/pfile.

Solution :
create spfile from memory/pfile;
shutdown the database and start it again.