# /usr/bin/java -jar apps/TLS-Server-Scanner.jar -connect www.bbc.co.uk:443

Exception in thread "main" java.lang.UnsupportedClassVersionError: de/rub/nds/tlsscanner/serverscanner/Main has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0

Great. But what do I need to do to fix it?
#CrapErrorMessage

@tdp_org upgrade /usr/bin/java or recompile the .jar with an older javac/options

@falken Thanks 🙌🏻 - but my point is that the message doesn't tell me any of that. I installed java from java.com which i presume would be the latest version. Turns out not to be, or that maybe it's something different than that - JRE, JDK, Java - i don't really know what they do specifically. The ecosystem assumes *loads* of knowledge. I just find java super frustrating as a user, not saying anything else is perfect by any means but this is the worst IMO.

@falken That said, do you know how i'd upgrade `/usr/bin/java`? As I say, i downloaded it from java.com so i'd assume that'd be latest wouldn't it?

@tdp_org Java class file version of 52 corresponds to Java 8, which is ancient. Looks like you are trying to run code compiled for Java 11.

I doubt you actually downloaded Java 8, so it might be more of a $PATH problem.

Its also likely that your distro has a version of Java greater than 11 in its package manager too, I try that first.