Note: This has been fixed in OpsCenter 6.0.1
OpsCenter uses the JVM starting in 6.0 and, as such, it needs to locate the location of the Java process before it can begin its startup process. In certain rare scenarios, it is possible that the script that locates the Java process can freeze, thus preventing OpsCenter from fully starting up.
If OpsCenter starts up, but there is no logging and you cannot access it via the browser, it's possible that it is frozen during the startup process.
If you run
ps -aux | grep opscenter and do not see the process begin with the path to Java, it's likely you've run into this problem.
To confirm, run
bash /usr/share/opscenter/bin/find-java with the same user that runs OpsCenter. If it does not immediately return with the location of the Java process, you've hit this issue.
This bug has been logged internally under OPSC-9344.
To fix this problem, simply set an environmental variable, JAVA_HOME and set it to the path of your JVM. Be sure to do this logged in as the user that runs OpsCenter.