I setup a new Windows 2016 Server VM on vmware and I ran the installer for 6.11 and everything is progressing fine. I get to "Connect to your Database" and choose My Own Database for SQL (2012) and enter all the information and it connects without an issue and I can see that tables have been created.
It goes through the install and then fails with an HTTP Status 500 - Internal Server Error
I changed the SQL User password and removed special characters, verified that the SQL user has ALL the permissions to the DB, I tried express install, I tried running the setup from IE and Chrome, I disabled Antivirus, Tried both FQDN & IP of SQL Server and each time I removed the installation and tried a reinstall and they all failed, I installed Java and tried the install from the .zip file but that didn't work.
confluence140918115552-stdout.2018-09-14.log
confluence140918115552-stderr.2018-09-14.log
commons-daemon.2018-09-14.log
catalina.2018-09-14.log
atlassian-confluence.log