Github user rouckas commented on the issue:
https://github.com/apache/zeppelin/pull/2231
I was also running into this issue with Zeppelin 0.7.3, Livy 0.5.0 (0.4.0),
and Spark 2.3.0 (or 2.2.1). The only solution I found was to downgrade to
Zeppelin 0.6.2.---
