[java] IntelliJ: Error:java: error: release version 5 not supported

I've done most things you are proposing with Java compiler and bytecode and solved the problem in the past. It's been almost 1 month since I ran my Java code (and back then everything was fixed), but now the problem appeared again. Don't know why, pretty annoyed though!

This time the solution was: Right click to project name -> Open module settings F4 -> Language level ...and there you can define the language level your project/pc is.

No maven/pom configuration worked for me both in the past and now and I've already set the Java compiler and bytecode at 12.