PROBLEM:

After successful db upgrade, I tried to update the compatible parameter and restart the database. I got below error.

 

SOLUTION:

The error is because, I have enabled flashback and created a guaranteed restore point, before the upgrade. So while trying to update the compatible parameter, it is not allowing. Because ,once compatible parameter is changed, we can’t downgrade.

To fix it, we need to drop the restore point. Follow below steps:

 

Check the flashback restore point and drop it:

Now update the compatible parameter in spfile and restart