What does this mean?


[2014-02-14 10:39:40.346] DEBUG: Will pop block 5073332198957728923 at height 66148
[2014-02-14 10:39:40.347] DEBUG: Will pop block 8348856438008341233 at height 66147
[2014-02-14 10:39:40.348] DEBUG: Reversal of alias assignment not supported
[2014-02-14 10:39:40.348] DEBUG: Popping off last block not possible, will do a rescan
[2014-02-14 10:39:40.349] Re-scanning blockchain...
[2014-02-14 10:39:54.734] ...Done
[2014-02-14 10:39:54.737] DEBUG: Generate block failed: Previous block id doesn't match