dovecot - May 2014 - dovecot.map.index corrupted: missing map extension

Hello,

I have a dovecot setup on top of NFS server, and i get this error on some
accounts:

Warning: fscking index file ..../cache/storage/dovecot.map.index
Warning: mdbox .../mdbox/storage: rebuilding indexes
Error: mdbox map.../cache/storage/dovecot.map.index corrupted: missing map
extension

I tried force-resync, index and cant rebuild the indexes, any idea how to
repair then?

Thanks

Dovecot version: 2.1.17