Seen the following message below during the installer of iDash:
ORA-02296: cannot enable (IDASHSIT.) - null values found
ORA-02441: Cannot drop nonexistent primary key
Release : 12.1.02
Verify the DB schema against the schema set out in IDASH_HOME/install/oracle/alltables.sql, and as long as the table definitions, keys, and indexes match up, you should be good to go.