RuntimeError: Java Gateway -Prozess, bevor er die Port -Nummer -Site gesendet hat: stackoverflow.com

One possible reason is JAVA_HOME is not set because java is not installed.
at sc = pyspark.SparkConf(). I solved it by running

!sudo add-apt-repository ppa:webupd8team/java
!sudo apt-get update
!sudo apt-get install oracle-java8-installer
Wide-eyed Weevil