Locking a Maildir, for e.g. backups, isn't possible anymore thru /usr/libexec/dovecot/maildirlock. Usage: /usr/libexec/dovecot/maildirlock /path/to/maildir 10 Panic: BUG: No IOs or timeouts set. Not waiting for infinity. Error: Raw backtrace: /usr/lib64/dovecot/libdovecot.so.0(+0xd9cde) [0x7f6d6596ecde] -> /usr/lib64/dovecot/libdovecot.so.0(+0xd9d21) [0x7f6d6596ed21] -> /usr/lib64/dovecot/libdovecot.so.0(i_fatal+0) [0x7f6d658d2962] -> /usr/lib64/dovecot/libdovecot.so.0(+0xf1f4c) [0x7f6d65986f4c] -> /usr/lib64/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x36) [0x7f6d659899f6] -> /usr/lib64/dovecot/libdovecot.so.0(io_loop_handler_run+0x4d) [0x7f6d6598821d] -> /usr/lib64/dovecot/libdovecot.so.0(io_loop_run+0x38) [0x7f6d65988438] -> /usr/libexec/dovecot/maildirlock(main+0x25b) [0x5565b414d25b] -> /lib64/libc.so.6(__libc_start_main+0xe7) [0x7f6d654ece77] -> /usr/libexec/dovecot/maildirlock(_start+0x2a) [0x5565b414d31a] There is a related mailing-list protocol here https://www.mail-archive.com/dovecot@dovecot.org/msg74800.html. Seems there is a bug within maildirlock itself, where it requires a time unit but nothing will work.
FYI: Same for =net-mail/dovecot-2.3.5.2
2.3.7.2 too