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

ORA-00383: 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_<n>K_cache_size to zero while there were still online tablespaces with  blocksize <n>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.