You have provided almost no background information, Mark. This seems like a Java program error.
Which application is it? How are you trying to install it?
sorry, I’m new at this.
Im trying to install opendaylight controller .
when i use the command ( export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-amd64 )
then the command ( ./karaf ) this appears.