title: Cassandra "Detected unreadable sstables " Error
body: <p>On my windows box, after a graceful restart for windows update, I get the following error in Cassandra (2.2.0) and it will not start:</p>
  
  <p>ERROR 10:36:41 Detected unreadable sstables D:\cassandra_data\data\gputptest-abcdedf-5040777060fe11e5a8557fcd8340170b-KeyCache-b.db,D:\cassandra_data\data\OpsCenter-events_timeline-afbbeee05cea11e59ba77fcd8340170b-KeyCache-b.db,D:\cassandra_data\data\system-IndexInfo-9f5c6374d48532299a0a5094af9ad1e3-KeyCache-b.db,...., please check NEWS.txt and ensure that you have upgraded through all required intermediate versions, running upgradesstables</p>
  
  <p>Any suggestion how I can recover the database? Or, at least drop those unreadable sstables and recover the rest?</p>