Panic: Module context expire_mail_user_module missing (Debian 10)

[Thomas Krause]

Hi all,
I tried to migrate a mailserver from Debian 9 (Dovecot 2.2.27) to
Debian 10 (Dovecot 2.3.4.1). I moved the mail-partition and
/etc/dovecot from the old to the new server. Dovecot started with
2 warnings. When trying to fetch mails via pop3 the server crashes:


Aug  1 16:56:47 mail19 dovecot: pop3-login: Login: user=<testuser>, 
rip=::1, mpid=22394, session=<rutwcw+PRp4AAAAAAAAAAAAAAAAAAAAB>
Aug  1 16:56:47 mail19 dovecot: 
pop3(testuser)<22394><rutwcw+PRp4AAAAAAAAAAAAAAAAAAAAB>: Panic: Module 
context expire_mail_user_module missing
Aug  1 16:56:47 mail19 dovecot: 
pop3(testuser)<22394><rutwcw+PRp4AAAAAAAAAAAAAAAAAAAAB>: Error: Raw 
backtrace: /usr/lib/dovecot/libdovecot.so.0(+0xdb13b) [0x7fd14ea7713b] 
-> /usr/lib/dovecot/libdovecot.so.0
(+0xdb1d1) [0x7fd14ea771d1] -> 
/usr/lib/dovecot/libdovecot.so.0(+0x4a001) [0x7fd14e9e6001] -> 
/usr/lib/dovecot/modules/lib20_expire_plugin.so(+0x23b2) 
[0x7fd14e7953b2] -> /usr/lib/dovecot/libdovecot-storage.so.0
(hook_mailbox_allocated+0x89) [0x7fd14eb89409] -> 
/usr/lib/dovecot/libdovecot-storage.so.0(mailbox_alloc+0xda) 
[0x7fd14eb84c5a] -> dovecot/pop3(client_init_mailbox+0x58) 
[0x55781fb5fba8] -> dovecot/pop3(+0x5645)
  [0x55781fb5e645] -> dovecot/pop3(+0x5882) [0x55781fb5e882] -> 
/usr/lib/dovecot/libdovecot.so.0(+0x6f601) [0x7fd14ea0b601] -> 
/usr/lib/dovecot/libdovecot.so.0(+0x6f97b) [0x7fd14ea0b97b] -> 
/usr/lib/dovecot/libdo
vecot.so.0(+0x7030d) [0x7fd14ea0c30d] -> 
/usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x6f) [0x7fd14ea8d5ef] 
-> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x136) 
[0x7fd14ea8ebe6] -> /usr/l
ib/dovecot/libdovecot.so.0(io_loop_handler_run+0x4c) [0x7fd14ea8d68c] -> 
/usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7fd14ea8d7f0] -> 
/usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7fd14e
a0dfd3] -> dovecot/pop3(main+0x2cf) [0x55781fb5e13f] -> 
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xeb) [0x7fd14e7f909b] 
-> dovecot/pop3(_start+0x2a) [0x55781fb5e29a]
Aug  1 16:56:47 mail19 dovecot: 
pop3(testuser)<22394><rutwcw+PRp4AAAAAAAAAAAAAAAAAAAAB>: Fatal: master: 
service(pop3): child 22394 killed with signal 6 (core dumps disabled - 
https://dovecot.org/bugreport.h
tml#coredumps)

What can I do? I tried to enable core dumps (installed systemd-coredump 
and modified limits.conf)
but it didn't work.

Best regards,
Thomas.