I just ran into this issue as well and it seems that the root user is not using Java 8 which is required to start Cassandra.
=> java -version
java version "1.8.0_40"
Java™ SE Runtime Environment (build 1.8.0_40-b26)
Java HotSpot™ 64-Bit Server VM (build 25.40-b25, mixed mode)
=> sudo java -version
java version "1.7.0_101"
OpenJDK Runtime Environment (IcedTea 2.6.6) (7u101-2.6.6-0ubuntu0.14.04.1)
OpenJDK 64-Bit Server VM (build 24.95-b01, mixed mode)
I did some digging and found that the alternatives were not set up correctly. To fix it you can run
=> echo ‘3’ | sudo update-alternatives --config java
There are 3 choices for the alternative java (providing /usr/bin/java).
Selection Path Priority Status
- 0 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 auto mode
1 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java 1071 manual mode
2 /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java 1069 manual mode
3 /usr/lib/jvm/jdk1.8.0/bin/java 1 manual mode
Press enter to keep the current choice[*], or type selection number:
You should do this in the machine.pre section of your circle.yml so that Cassandra can start after