This is a quick post about an issue that I faced while trying to start one database yesterday.
When I was trying to open one 12cR1 database, I got the following error:
SYS SQL>alter database open;
alter database open
*
ERROR at line 1:
ORA-38760: This database instance failed to turn on flashback database

The database status was “mounted”:

From the alert log, it is clear that flashback mode is enabled in the database and someone has mistakenly deleted flashback log physically. So, I tried to disable the flashback mode as follows:

After that, I tried to open the database again but I received the same set of the above errors.
Did someone create a restore point, let us check:

So, this is the reason behind this issue. There is a guaranteed restore point, and its flashback logs were physically deleted. Let us drop this restore point:

Now let us try to open the database:

Done !
Thanks
Ahmed