If we start the installation process and after entering the license information and during the DB setup, we try to open the Confluence instance, we will get an error 500 messages, and DB will get corrupted. The issue is also visible if we migrate instances from the Server to DC.
The only solution, in that case, would be to destroy the data in db, delete confluence.cfg.xml and restart the instance.
This can happen due to multiple reasons, like monitoring tool, or load balancer checks.
Therefore it would be good to have a safety mechanism, that would redirect the Confluence request, for example, based on session, to a static page until installation is finished.