Error loading webmail

When I try to open webmail (https://host.hostname.com:2031/webmail) I got to the login screen, no matter what I try to login as but after I press login I got an error 500, page isn't working. Any ideas?

any one?

you need to check your logs
http://wiki.centos-webpanel.com/service-log-paths

This is what I got:

[20-Apr-2017 20:13:55 UTC] PHP Fatal error:  Uncaught Error: Class 'Net_IDNA2' not found in /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/bootstrap.php:405
Stack trace:
#0 /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/rcube_utils.php(891): idn_to_ascii('localhost')
#1 /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/rcube_utils.php(869): rcube_utils::idn_convert('localhost', true)
#2 /usr/local/cwpsrv/var/services/roundcube/program/include/rcmail.php(600): rcube_utils::idn_to_ascii('localhost')
#3 /usr/local/cwpsrv/var/services/roundcube/index.php(109): rcmail->login('user@domain...', 'password', 'localhost', true)
#4 {main}
  thrown in /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/bootstrap.php on line 405

PHP Fatal error:  Uncaught Error: Class 'Net_IDNA2' not found

if you don't have a working idn_to_utf8 function.This class is used. It should be included into PHP 5.3. In Debian, this is
php5-intl package. you check whether intl.so was loaded ?

This is what I got:

[20-Apr-2017 20:13:55 UTC] PHP Fatal error:  Uncaught Error: Class 'Net_IDNA2' not found in /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/bootstrap.php:405
Stack trace:
#0 /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/rcube_utils.php(891): idn_to_ascii('localhost')
#1 /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/rcube_utils.php(869): rcube_utils::idn_convert('localhost', true)
#2 /usr/local/cwpsrv/var/services/roundcube/program/include/rcmail.php(600): rcube_utils::idn_to_ascii('localhost')
#3 /usr/local/cwpsrv/var/services/roundcube/index.php(109): rcmail->login('user@domain...', 'password', 'localhost', true)
#4 {main}
  thrown in /usr/local/cwpsrv/var/services/roundcube/program/lib/Roundcube/bootstrap.php on line 405

I also got this same issue if anyone knows please help