Hello, after upgrading from 2.1.17 to 2.2.18 i have a specific Inbox which causes a crash on dovecot: Jun 19 09:28:03 hostname dovecot: imap(username): Error: Raw backtrace: /usr/lib/dovecot/libdovecot.so.0(+0x7075f) [0x7f9298c4375f] -> /usr/lib/dovecot/libdovecot.so.0(+0x707be) [0x7f9298c437be] -> /usr/lib/dovecot/libdovecot.so.0(i_fatal+0) [0x7f9298bf11aa] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x2bd9a) [0x7f9298ee2d9a] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x98f8b) [0x7f9298f4ff8b] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_mail_get_first_header+0xb9) [0x7f9298f502c9] -> /usr/lib/dovecot/libdovecot-storage.so.0(mail_get_first_header+0x38) [0x7f9298ee3d18] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0xabfa2) [0x7f9298f62fa2] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0xac1e2) [0x7f9298f631e2] -> /usr/lib/dovecot/libdovecot.so.0(i_stream_read+0x68) [0x7f9298c4d118] -> /usr/lib/dovecot/libdovecot.so.0(i_stream_read_data+0x3d) [0x7f9298c4da9d] -> /usr/lib/dovecot/libdovecot.so.0(message_parse_header_next+0x65) [0x7f9298c33065] -> /usr/lib/dovecot/libdovecot.so.0(message_parse_header+0x38) [0x7f9298c338d8] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_mail_parse_headers+0x80) [0x7f9298f4f940] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x98cca) [0x7f9298f4fcca] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_mail_get_first_header+0xb9) [0x7f9298f502c9] -> /usr/lib/dovecot/libdovecot-storage.so.0(mail_get_first_header+0x38) [0x7f9298ee3d18] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0x9a85a) [0x7f9298f5185a] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_mail_get_date+0x92) [0x7f9298f51972] -> /usr/lib/dovecot/libdovecot-storage.so.0(mail_get_date+0x36) [0x7f9298ee3b76] -> /usr/lib/dovecot/libdovecot-storage.so.0(+0xa3113) [0x7f9298f5a113] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_sort_list_add+0x31) [0x7f9298f5a471] -> /usr/lib/dovecot/libdovecot-storage.so.0(index_storage_search_next_nonblock+0x3d) [0x7f9298f5801d] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_search_next_nonblock+0x27) [0x7f9298eecd67] -> dovecot/imap [username ip.ip.ip.ip UID SORT](+0x1e7f7) [0x7f92994117f7] -> dovecot/imap [username ip.ip.ip.ip UID SORT](imap_search_start+0xf1) [0x7f9299411c41] -> dovecot/imap [username ip.ip.ip.ip UID SORT](cmd_sort+0x25b) [0x7f9299407c4b] -> dovecot/imap [username ip.ip.ip.ip UID SORT](command_exec+0x4d) [0x7f929940c40d] Mailboxformat is mbox. I think reason was a damaged Index in ~username/mail/.imap/INBOX/ I removed this folder and immediately errors are gone and Mailbox was readable again. Never noticed this kind of errors for years on 2.1.17, maybe this helps to find a Bug in Code. Thanks, Hajo