How to fix a bug in Postfix?

Question

linux

Hello! Tell me, for some reason, letters are not coming.
I use a bunch of Dovecot + Postfix + MySQL (backend)
Errors in the logs:

Jul 25 12:57:59 vm-69283c2b postfix/smtpd[27057]: fatal: connect #11 to subsystem private/proxymap: Connection refused
Jul 25 13:00:40 vm-69283c2b postfix/smtpd[27110]: fatal: connect #11 to subsystem private/proxymap: Connection refused

/var/log/mail.log.syslog:

spoiler

Jul 25 13:01:41 vm-69283c2b postfix/smtpd[27161]: warning: connect #1 to subsystem private/proxymap: Connection refused
Jul 25 13:01:51 vm-69283c2b postfix/smtpd[27161]: warning: connect #2 to subsystem private/proxymap: Connection refused
Jul 25 13:02:01 vm-69283c2b postfix/smtpd[27161]: warning: connect #3 to subsystem private/proxymap: Connection refused
Jul 25 13:02:11 vm-69283c2b postfix/smtpd[27161]: warning: connect #4 to subsystem private/proxymap: Connection refused
Jul 25 13:02:21 vm-69283c2b postfix/smtpd[27161]: warning: connect #5 to subsystem private/proxymap: Connection refused
Jul 25 13:02:31 vm-69283c2b postfix/smtpd[27161]: warning: connect #6 to subsystem private/proxymap: Connection refused
Jul 25 13:02:41 vm-69283c2b postfix/smtpd[27161]: warning: connect #7 to subsystem private/proxymap: Connection refused
Jul 25 13:02:51 vm-69283c2b postfix/smtpd[27161]: warning: connect #8 to subsystem private/proxymap: Connection refused
Jul 25 13:03:01 vm-69283c2b postfix/smtpd[27161]: warning: connect #9 to subsystem private/proxymap: Connection refused
Jul 25 13:03:11 vm-69283c2b postfix/smtpd[27161]: warning: connect #10 to subsystem private/proxymap: Connection refused
Jul 25 13:03:21 vm-69283c2b postfix/smtpd[27161]: fatal: connect #11 to subsystem private/proxymap: Connection refused
Jul 25 13:03:22 vm-69283c2b postfix/master[26485]: warning: process /usr/lib/postfix/sbin/smtpd pid 27161 exit status 1
Jul 25 13:03:22 vm-69283c2b postfix/master[26485]: warning: /usr/lib/postfix/sbin/smtpd: bad command startup -- throttling