Another afternoon spent helping my son learn linux for hosting his own minecraft server.
The problem today was that the version of forge that he wanted to run was not compatible with the version of java we were using. There was a jdk update a while back that broke the older version of forge. We upgraded to the latest version of this version of forge to fix the issue.
His server is setup so that minecraft servers run as a service, and each version of forge is installed in it's own directory. He can then run servers using sytstemctr commands. He has multiple version of forge installed depending on the mods he wants to use, and sometimes he will go months between running certain versions. This time he was running a version that he had not run in a few month, and since java was updated since he last ran it, forge would not start. It was a security update, so rolling back the java version (which is what the forums suggested) was not an option. Instead we checked for forge version updates and found one that was five months old.
Things we learned / reinforced.
reading and finding server logs
reading stack traces
searching google for jvm error messages
upgrading the forge version jar on the server
running commands as another user
