title: How to make a Programm written in jdk12 on windows over intellij and compiled to .jar run in Linux with openJDK
body: <p>i have developed a small server, which works perfecctly in windows. i compiled this to a .jar file and pushed it to my linux server. I am unable to run the programm because of a version error. i found many informations on the internet but nothing solved my problem.</p>
  
  <p>i developed it in windows with intellij using oracle jdk 12 and compiled it allready.
  i have installed the default jdk (IcedTea 2.6.19) in my debian linux. i have also unzipped an openjdk 13 tar file but i dont know how and even if it is possible to execute this.</p>
  
  <p>Exception in thread "main" java.lang.UnsupportedClassVersionError: </p>
  
  <p>MultiThreadServer : Unsupported major.minor version 56.0</p>
  
  <p>i would appriciate a solution. If i have to install an oracle jdk on my linux i would like to know how. i am new in windows and dont know how</p>