Hello there,
I'm currently in the process of setting up a 18.1 server on linux (without desktop), but when I start the "./run.sh" command, I get the following error:
 

Error occurred during initialization of boot layer
java.lang.module.FindException: Error reading module: libraries/cpw/mods/bootstraplauncher/1.0.0/bootstraplauncher-1.0.0.jar
Caused by: java.lang.module.InvalidModuleDescriptorException: Unsupported major.minor version 60.0

update-alternatives query for Java
 

Name: java
Link: /usr/bin/java
Slaves:
 java.1.gz /usr/share/man/man1/java.1.gz
Status: auto
Best: /usr/lib/jvm/java-11-openjdk-amd64/bin/java
Value: /usr/lib/jvm/java-11-openjdk-amd64/bin/java

Alternative: /usr/lib/jvm/java-11-openjdk-amd64/bin/java
Priority: 1111
Slaves:
 java.1.gz /usr/lib/jvm/java-11-openjdk-amd64/man/man1/java.1.gz

Alternative: /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
Priority: 1081
Slaves:
 java.1.gz /usr/lib/jvm/java-8-openjdk-amd64/jre/man/man1/java.1.gz

I have not changed or delete any file.

oh. ok. thank you