Oracle Message ORA-00383 - DEFAULT cache for blocksize string cannot be reduced to zero

ERROR	DEFAULT cache for blocksize string cannot be reduced to zero
CAUSE	User attempted to reduce db_cache_size to zero, or attempted to to reduce db_K_cache_size to zero while there were still online tablespaces with blocksize K. Note that since the SYSTEM tablespace cannot be taken offline, it is always illegal to set db_cache_size to zero.
ACTION	Offline any tablespaces with the corresponding blocksize and then perform the operation again.