If you build cassandra from source (i.e. trunk, cassandra-2.1) a version number such as 4.0-SNAPSHOT will be reported in the release_version column in the system.peers and system.local table.
Since 3.18.0, the driver is currently not able to handle this:
This occurs when the version in both the x.y-SNAPSHOT (4.0-SNAPSHOT) and x.y.z-SNAPSHOT (2.1.21-SNAPSHOT) formats.
The Version parsing has been improved to support a pre release part like '-SNAPSHOT'.