FTB server unable to start even after FTBInstall.sh

Long time user of MineOS though I have just recently come back after a long hiatus. I remember having this exact issue two years back and never actually found a solution so I figured it was about time to hop on the forum.

I have been trying to put up a FTB Revelations server but I find that even after using the FTBInstall.sh button the server will not start. (Classic FTB start issue, sometimes runs for a second then stops, etc.)

I have gone to the main terminal and manually run FTBInstall.sh and it ran without errors though I know that the webui button itself is working because the minecraft 1.12.jar shows up a short while after I press the button. As usual Vanilla servers are working fine, so on and so forth.

If anybody has some ideas or input I would love to hear back as I am completely stumped on this one.

First things first: when you go to the main terminal, are you doing it as your webui user (probably mc)?

Secondly, if you invoke the FTB revelations jar manually, does it start?

Does /var/log/mineos.log show any errors?

What’s the server jar selected in the webui to run?

Sorry for the absolutely ludicrous time between this reply. Life and all that.
After running the FTBInstall.sh it does not echo an error and the minecraft server.jar shows up without any issues.
Manually running the FTB server jar does not seem to do anything and the log only lists that it received requests to start the server.

{“level”:“info”,“message”:"[Server] received request “run_installer”",“timestamp”:“2019-04-09T17:02:22.336Z”}
{“level”:“info”,“message”:"[Server] 192.168.1.XXX issued command : “start”",“timestamp”:“2019-04-09T17:02:25.417Z”}
{“level”:“info”,“message”:"[Server] received request “start”",“timestamp”:“2019-04-09T17:02:25.418Z”}

This is all I can see.

which server jar are you trying to run?

I attempted to run FTBserver-1.12.2-
Running the standard minecraftserver.jar will start a vanilla server.
I also found by trying on another machine this in the logs after invoking ServerStart.sh:

Starting server
Unrecognized VM option ‘UseParNewGC’
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occured. Program will exit.

What kind of install of MineOS are you using?

What version of Java do you have installed?

The MineOS install is the manual installation over an Ubuntu server.
java version reports as 11. I attempted to install 8 specifically using

apt get openjdk-8-jre-headless

but received a message saying it is already the latest version.

Probably means you have 11 and 8 installed simultaneously.

Linux looks through the $PATH variable sequentially to find java and it’s finding wherever you installed 11.

apt-get is looking to install it at /usr/bin/java (probably) and it’s saying it’s finding it and then reporting ‘latest version’–as that is the latest version apt has/uses.

So you need to either remove Java 11 (I’m assuming it’s the one not working with your FTB) or remove the path that includes Java 11 from your root's environment.

Such adjustments might be in /etc/profile, or /root/.bash_profile, and so forth.