parameter cannot be modified because specified value is invalid

 ALTER SYSTEM SET db_4k_cache_size=128M

Error report -

ORA-02097: parameter cannot be modified because specified value is invalid

ORA-00384: Insufficient memory to grow cache

02097. 00000 -  "parameter cannot be modified because specified value is invalid"

*Cause:    Though the initialization parameter is modifiable, the modified

           value is not acceptable to the parameter.

*Action:   Check the DBA guide for range of acceptable values for this

           parameter.

Solution is to set 

show parameter sga_target;

alter system set sga_max_size=2G scope=spfile;

alter system set sga_target=1024M scope=spfile;

and the restart the Database server and try to run the command again it worked for me.

ALTER SYSTEM SET db_4k_cache_size=128M

System SET altered.