pulsar

there shouldn’t be problems.

but usually it is better to upgrade only if you have a good reason to do it.

at DataStax we have been using ZK 3.8.0 since Pulsar 2.8.x so I don’t expect surprises
for BookKeeper any version for 4.14.x onwards should work well, but I am not aware of any Pulsar clusters running the Bookies at 4.15.x or more recent.
that said, it is 100% compatible

Thanks Enrico, what are the major benefits of Zookeeper 3.8.x ?

a few features about security  and performance improvements

checkout the high lights here in the bottom
<https://zookeeper.apache.org/releases.html>