Corrupted index cache after migrating from maildir to mdbox

[Daniel Parthey]

I think you could try to simply delete dovecot.index.cache file and have dovecot automatically recreate it on the next delivery or login. And then see if the error messages go away for this mailbox.

With mdbox the dovecot.index file must not be deleted however, you would otherwise lose "seen" flags.

Anyway, better have a backup prepared, before deleting any files ;)

Regards
Daniel