To upgrade your Minecraft Server on Ubuntu to a more recent version of forge:
- Download the installer and universal package for the version of forge you want.
- Transfer them to the server.
- Run the installer: `java –jar forge-X.X.X-X.X.X.XXX–installer.jar —installServer`
- Restart the server: `java -Xms1024M -Xmx8192M -jar ~/minecraft/forge-1.12.2-14.23.3.2675-universal.jar noguiadsls`