A user reported this to me, and I'm seeing it too:
Hi all :)

After mail/dovecot upgrade to v2.3.7 it seems something went wrong with stat-writer...

IMAP and POP3 logs:

Jul 12 19:45:34 mail dovecot: imap-login: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/stats-writer), TRUE) failed: Invalid argument
Jul 12 19:45:34 mail dovecot: imap-login: Error: file_ostream.net_set_tcp_nodelay((conn:unix:login), TRUE) failed: Invalid argument
Jul 12 19:45:35 mail dovecot: imap: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/stats-writer), TRUE) failed: Invalid argument
Jul 12 19:45:35 mail dovecot: imap: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/auth-master), TRUE) failed: Invalid argument
Jul 12 19:45:35 mail dovecot: imap-login: Login: user=<someone@domain.tld>, method=PLAIN, rip=192.168.0.28, lip=192.168.0.1, mpid=47811, TLS, session=<aelAen+NKpDAqAAc>
Jul 12 19:45:41 mail dovecot: imap(someone@domain.tld)<47811><aelAen+NKpDAqAAc>: Connection closed (UID SEARCH finished 6.727 secs ago) in=128 out=2015 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0

Jul 12 19:51:21 mail dovecot: pop3-login: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/stats-writer), TRUE) failed: Invalid argument
Jul 12 19:51:21 mail dovecot: auth: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/stats-writer), TRUE) failed: Invalid argument
Jul 12 19:51:21 mail dovecot: pop3-login: Error: file_ostream.net_set_tcp_nodelay((conn:unix:login), TRUE) failed: Invalid argument
Jul 12 19:51:21 mail dovecot: pop3: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/stats-writer), TRUE) failed: Invalid argument
Jul 12 19:51:21 mail dovecot: pop3: Error: file_ostream.net_set_tcp_nodelay((conn:unix:/var/run/dovecot/auth-master), TRUE) failed: Invalid argument
Jul 12 19:51:21 mail dovecot: pop3-login: Login: user=<someone@domain.tld>, method=PLAIN, rip=192.168.0.33, lip=192.168.0.1, mpid=47877, TLS, session=<h+3jjn+NcPrAqAAh>
Jul 12 19:51:21 mail dovecot: pop3(someone@domain.tld)<47877><h+3jjn+NcPrAqAAh>: Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0

Ideas?

--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 214-642-9640 (c)     E-Mail: larryrtx@gmail.com
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