Hi, I had the same experience. I used the current dovecot and SOLR 5.2. It works with 4.10, so my first wild guess would be that there is a bug in dovecots url encoding sending to solr (they possibly updated some stuff in url handling? - don't know).
In SOLR 5.2 i created a core "mail3" and copied the config from my working 4.10 installation. Indexing new messages seem to work, but searching gives a http 400 error. Firing up the query in solrs web interface works ... one of my test cases was select?fl=uid,score&rows=3&sort=uid+asc&q=subject:%22blubb%22&fq=%2Bbox:b624920e60057c554e4a0000df211752+%2Buser:%22user%22 For further reference see http://mail-archives.apache.org/mod_mbox/lucene-solr-user/201506.mbox/browser Could the devs please have a look at this, it might hopefully be just a small change. regards, infoomatic > Gesendet: Freitag, 12. Juni 2015 um 11:19 Uhr > Von: "Nick Rosier" <nick+dove...@bunbun.be> > An: dovecot@dovecot.org > Betreff: fts_solr Bad Request / BUG: Unknown internal error > > Hi, > > yesterday I created a new mailbox; ever since (and only for the new > mailbox) I am getting these errors: > > 2015-06-12T00:00:29.808526+02:00 mail dovecot: > indexer-worker(x...@example.com): Error: fts_solr: Lookup failed: Bad > Request > 2015-06-12T00:00:29.808560+02:00 mail dovecot: > indexer-worker(x...@example.com): Error: Mailbox INBOX: Status lookup > failed: BUG: Unknown internal error > > Is this a known issue? > Rgds, > N. >