Since i cannot post a bug on the bug tracker (registration disabled), i try here. I'm using the git master version and i met this error on the postfix.log
This happens only when i try to send an email with roundcube...
Mar 1 18:33:50 server roundcube: PHP Catchable fatal error: session_regenerate_id(): Failed to create(read) session ID: user (path: /var/lib/php/sessions) in /opt/www/roundcubemail-git/program/lib/Roundcube/rcube_session.php on line 436
Mar 1 18:40:26 server roundcube: PHP Fatal error: Uncaught Error: Class 'Mail_mime' not found in /opt/www/roundcubemail-git/program/steps/mail/sendmail.inc:361#012Stack trace:#012#0 /opt/www/roundcubemail-git/index.php(291): include_once()#012#1 {main}#012 thrown in /opt/www/roundcubemail-git/program/steps/mail/sendmail.inc on line 361
Consider i'm using the PHP 7 with Apache 2.4...
For PHP7 you need Roundcube 1.2.
As I said i'm using the github version of roundcube (the last one, 1.2-git)...
(https://dl.dropboxusercontent.com/u/89718989/bandicam%202016-03-01%2021-29-48-158.jpg)
Besides both "sendmail.inc" files (from the 1.2 released on november and from the 1.2-git) match, so the error doesn't change...
Most likely you didn't install dependencies (/vendor directory). As for the session error this is your php installation issue. Looks like php can't write to /var/lib/php/sessions.
Ok resolved, i forgot to enable the session module for PHP xD :P