I\'m currently experimenting around with Cassandra.
On the client-side (with Hector) I look up a few keys like this:
ColumnFamilyResult
To me it looks like it was a bug.
With the later version (1.1.5) the error disappeared. At least for me.
This looks like https://issues.apache.org/jira/browse/CASSANDRA-4687, which is not yet fixed. A workaround is to disable the key cache.
This is either https://issues.apache.org/jira/browse/CASSANDRA-4687 or https://issues.apache.org/jira/browse/CASSANDRA-5202 You can run the command "nodetool invalidatekeycache" on all of the server showing the error. If it keeps coming back you may want to disable key cache. If it is 5202 it should only happen after dropping and recreating a column family using the same name.