Dovecot error - User () doesn't have home dir set, disabling duplicate database

I have a message into the logs of dovecot:

lda(domain): Error: User […] doesn’t have home dir set, disabling duplicate database

But the mail arrives correctly, and no problems at all.
I searched on google , but I have not found answers

In configuration I have only:
dovecot-ldap.conf
user_attrs = sAMAccountName=mail=maildir:/var/www/mail/%d/%n/Maildir
and 10-mail.conf
mail_location = maildir:/var/www/mail/%d/%n

how to correct the logs?