Here is the answer of Konsole and an extract of the log, which says the same thing.
Thanks for your help
tail -0f /var/log/dovecot.log
Apr 19 08:02:56 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 19 08:03:07 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
log:
Apr 17 22:00:48 dovecot: Info: Dovecot v1.2.17 starting up (core dumps disabled)
Apr 17 22:00:48 dovecot: Info: Generating Diffie-Hellman parameters for the first time. This may take a while..
Apr 17 22:00:48 auth(default): Error: LDAP: Can't connect to server: 127.0.0.1:389
Apr 17 22:00:48 auth(default): Error: LDAP: Can't connect to server: 127.0.0.1:389
Apr 17 22:00:56 ssl-build-param: Info: SSL parameters regeneration completed
Apr 17 22:17:13 auth(default): Error: LDAP: Can't connect to server: 127.0.0.1:389
Apr 17 22:17:20 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 22:18:04 auth(default): Error: LDAP: Can't connect to server: 127.0.0.1:389
Apr 17 22:18:11 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 22:27:48 dovecot: Warning: Killed with signal 15 (by pid=16615 uid=0 code=kill)
Apr 17 22:29:30 dovecot: Info: Dovecot v1.2.17 starting up (core dumps disabled)
Apr 17 22:29:31 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 22:57:05 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 22:57:16 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 22:57:40 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 22:57:51 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 23:13:35 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 23:13:46 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 23:13:52 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 23:14:03 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 17 23:14:08 auth(default): Error: LDAP: binding failed (dn cn=vmail,dc=example,dc=com): Invalid credentials
Apr 17 23:14:19 imap-login: Info: Aborted login (auth failed, 1 attempts): user=<www@collectifagdsanduze.info>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured
Apr 18 01:15:55 dovecot: Warning: Killed with signal 15 (by pid=9118 uid=0 code=kill)
ZhangHuangbin wrote:Well, user authentication failed.
There must be some related error log in Dovecot log file (/var/log/dovecot.log), could you please paste them here?
You can get error log with below steps:
1) Open a terminal, monitor Dovecot log file with below command (run as root):
# tail -0f /var/log/dovecot.log
2) Now login to Roundcubemail. If it failed again, there must be some error log output in terminal.
If there's not much log, please set/update 'mail_debug = yes' in /etc/dovecot/dovecot.conf, restart Dovecot service and repeat above steps.