Any query that performed through C# client results with exception in Cassandra system.log and debug.log
It is strange to see 0.0.0.0 instead of standart localhost address 127.0.0.1
It looks like you are forcibly closing the connection by exiting the .NET process.
You should call Cluster.Shutdown() before app exit.
I assume the issue no longer appears after using Cluster.Shutdown() / Dispose, so I'll close it.
Feel free to reopen if the issue persists.