When opening claws-mail, a warning popped up saying that the address book database could not be opened. It was a surprise to me since I haven't modified the address book in a while. My contacts disappeared from the address book UI, but they are still located in the directory ~/.claws-mail/addrbook/
How to rebuild the addressbook database or otherwise restore contacts?
If possible, please quote the exact warning message.
yes, unfortunately I lost the warning message. In any case, I resolved the problem by copying the xml files to a different directory and then moving those that contained contact back in one by one. I also realized that more than just the contacts were affected: all the plugins were disabled and I lost the configuration of one email account. Apologies for a lack of detail on this one!