I could to reply to the original thread: https://www.mail-archive.com/dovecot@dovecot.org/msg85204.html

But I managed to get a stack trace of the error:

root@mail:~ # lldb /usr/local/libexec/dovecot/auth (lldb) target create "/usr/local/libexec/dovecot/auth" Current executable set to '/usr/local/libexec/dovecot/auth' (x86_64). (lldb) run Process 54354 launched: '/usr/local/libexec/dovecot/auth' (x86_64) Error: stats: open(old-stats-user) failed: No such file or directory Panic: file http-client.c: line 646 (http_client_context_close): assertion failed: (cctx->clients_list == NULL) Process 54354 stopped libc.so.7`__sys_thr_kill:

• thread #1, name = 'auth', stop reason = signal SIGABRT frame #0: 0x000000080159f33a libc.so.7`__sys_thr_kill + 10

-> 0x80159f33a <+10>: jb 0x80159d498 0x80159f340 <+16>: retq 0x80159f341: int3 0x80159f342: int3 (lldb) bt all libdovecot.so.0`default_fatal_finish(type=LOG_TYPE_PANIC, status=0) at

• thread #1, name = 'auth', stop reason = signal SIGABRT
  • frame #0: 0x000000080159f33a libc.so.7__sys_thr_kill + 10 frame #1: 0x0000000801517c74 libc.so.7__raise + 52 frame #2: 0x00000008015c9109 libc.so.7`abort + 73 frame #3: 0x00000008012e606b

failures.c:465:3 frame #4: 0x00000008012e3f7c libdovecot.so.0fatal_handler_real(ctx=0x00007fffffffe610, format="file %s: line %d (%s): assertion failed: (%s)", args=0x00007fffffffe5f0) at failures.c:477:2 frame #5: 0x00000008012e3f14 libdovecot.so.0default_fatal_handler(ctx=0x00007fffffffe610, format="file %s: line %d (%s): assertion failed: (%s)", args=0x00007fffffffe5f0) at failures.c:485:2 frame #6: 0x00000008012e4253 libdovecot.so.0i_panic(format="file %s: line %d (%s): assertion failed: (%s)") at failures.c:530:2 frame #7: 0x000000080124f2ed libdovecot.so.0http_client_context_close(cctx=0x000000080205c048) at http-client.c:646:2 frame #8: 0x000000080124ef22 libdovecot.so.0http_client_global_context_ioloop_switched(prev_ioloop=0x0000000802030640) at http-client.c:710:3 frame #9: 0x00000008013102e4 libdovecot.so.0io_loop_set_current(ioloop=0x0000000000000000) at ioloop.c:982:4 frame #10: 0x00000000010aa0be authdriver_pgsql_set_state(db=0x0000000802092200, state=SQL_DB_STATE_IDLE) at driver-pgsql.c:103:3 frame #11: 0x00000000010a9ff0 authconnect_callback(db=0x0000000802092200) at driver-pgsql.c:206:3 frame #12: 0x000000080130f3b2 libdovecot.so.0io_loop_call_io(io=0x00000008020105c0) at ioloop.c:737:2 frame #13: 0x0000000801313e0b libdovecot.so.0io_loop_handler_run_internal(ioloop=0x0000000802030640) at ioloop-kqueue.c:164:4 frame #14: 0x000000080130fa15 libdovecot.so.0io_loop_handler_run(ioloop=0x0000000802030640) at ioloop.c:789:2 frame #15: 0x000000080130f8fa libdovecot.so.0io_loop_run(ioloop=0x0000000802030640) at ioloop.c:762:3 frame #16: 0x00000000010a7eef authdriver_pgsql_wait(_db=0x0000000802092200) at driver-pgsql.c:1279:3 frame #17: 0x00000000010a4c59 authsql_wait(db=0x0000000802092200) at sql-api.c:820:3 frame #18: 0x00000000010a7fc0 authdriver_pgsql_get_flags(db=0x0000000802092200) at driver-pgsql.c:306:3 frame #19: 0x00000000010a2fa9 authsql_get_flags(db=0x0000000802092200) at sql-api.c:171:10 frame #20: 0x00000000010a585e authdriver_sqlpool_get_flags(_db=0x0000000802092000) at driver-sqlpool.c:450:9 frame #21: 0x00000000010a2fa9 authsql_get_flags(db=0x0000000802092000) at sql-api.c:171:10 frame #22: 0x000000000108c675 authpassdb_sql_init(_module=0x0000000802041ca8) at passdb-sql.c:281:10 frame #23: 0x000000000107d577 authpassdb_init(passdb=0x0000000802041ca8) at passdb.c:247:3 frame #24: 0x0000000001052a89 authauth_passdb_init(passdb=0x0000000802041ba8) at auth.c:308:2 frame #25: 0x0000000001051dbc authauth_init(auth=0x0000000802041b70) at auth.c:322:3 frame #26: 0x0000000001051d21 authauths_init at auth.c:427:3 frame #27: 0x0000000001050610 authmain_init at main.c:242:2 frame #28: 0x00000000010503ad authmain(argc=1, argv=0x00007fffffffeaf8) at main.c:391:2 frame #29: 0x000000000104ff7d auth_start(ap=<unavailable>, cleanup=<unavailable>) at crt1_c.c:75:7