FTS-Solr: indexer-worker does not find mailbox

[Marc Stürmer]

Greetings,

I am running Dovecot v. 2.2.13 on a Gentoo Box. Mail users are virtual, 
data for them is stored in a MySQL-DB, Sieve is enabled and deliver is 
the LDA in conjunction with Postfix.

This setup has been running for a few years now without problems, the 
configuration works.

Some weeks ago the setup was still on a Ubuntu 12.04 LTS box, and 
Dovecot was v. 2.0.9. I've installed a Tomcat there with Solr and 
configured the FTS-Solr plugin from Dovecot. Worked like a charm without 
any problems at all.

Now the same setup on the Gentoo box does not work at all; either 
indexer-worker does not find the directory or is just indexing 0 messages.

Solr is also installed again (v. 3.6.0) on Tomcat, and Solr is running 
properly. I checked it with my browser and the logs, they are showing no 
errors.

gentoo ~ # dovecot --version
2.2.13

dovecot -n:
http://pastebin.com/NqLfrbp8

dovecot-sql.conf:
http://pastebin.com/KLf4pjJZ

Debug log.
Nov 11 20:12:14 kraftzwerg dovecot: indexer-worker: Debug: auth input: 
mail at marc-stuermer.de home=/var/kunden/mail/ 
mail=maildir:marc/mail at marc-stuermer.de/ uid=9997 gid=9997
Nov 11 20:12:14 kraftzwerg dovecot: indexer-worker: Debug: Added userdb 
setting: mail=maildir:marc/mail at marc-stuermer.de/
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Effective uid=9997, 
gid=9997, home=/var/kunden/mail/
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Namespace : type=private, 
prefix=INBOX., sep=., inbox=yes, hidden=no, list=yes, subscriptions=yes 
location=maildir:marc/mail at marc-stuermer.de/
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: maildir++: 
root=marc/mail at marc-stuermer.de, index=, indexpvt=, control=, 
inbox=marc/mail at marc-stuermer.de, alt=
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Namespace INBOX.: 
marc/mail at marc-stuermer.de doesn't exist yet, using default permissions
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Namespace INBOX.: Using 
permissions from marc/mail at marc-stuermer.de: mode=0700 gid=default
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Namespace : type=private, 
prefix=, sep=, inbox=no, hidden=yes, list=no, subscriptions=no 
location=fail::LAYOUT=none
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: none: root=, index=, 
indexpvt=, control=, inbox=, alt=
Nov 11 20:12:14 kraftzwerg dovecot: 
indexer-worker(mail at marc-stuermer.de): Debug: Syncing mailbox 
INBOX.gentoo failed: Mailbox doesn't exist: INBOX.gentoo
Nov 11 20:12:14 kraftzwerg dovecot: imap(mail at marc-stuermer.de): Error: 
indexer failed to index mailbox INBOX.gentoo

So the question is: where's the error and how to fix it? I am kinda 
clueless right now.

Thanks in advance,
Marc