The chainstate is a temporary database that updates on every cycle of starting the node and it keeps a record of the blockchain status.  Forget trying to reindex.  Try to shut down and restart the node.  You will get the error but check if the  bitcoind program is running.  It takes a few minutes for bitcoind to rewrite the chainstate.  The program may run even with this error and will eventually overwrite the old corrupt data and run fine. 

More often shut down the apollo and start it up may get the download going again.  Trying to stop and start the node is less successful.  As long as bitcoind is running it will fix itself.  From experience, don't bother trying to reindex your chainstate or blockchain.  It is much easier to start a fresh blockchain download than trying to reindex.  The CPU is not fast enough.