Why do I need to link the database again after updaing from JIRA 7.0.0 to JIRA 8.4.1?

[JConstantine]

I created the second instance of JIRA on the same server.
I linked MySQL database to it.
I imported my data.

Than I updated JIRA from 7.0.0 to 8.4.1 and everything was fine except one thing.There was an error telling me to change "storage_engine" parameter to "default_storage_engine" in dbconfig.xml even though I have MySQL server 5.6. I did that,
restarted my machine and when I launch JIRA now the setup wizard starts again and I have to link an empty database again...I tried to change the parameter in dbconfig.xml again but that doesn't work.
I get this instead:

I'd appreciate some help.

[JConstantine]

Well...I changed "dbserver:3306" to "localhost:3306" and now it works.