PHP Deprecated warnings when taking actions in Roundcube

Symptoms

When taking actions in Roundcube, PHP Deprecated warnings are logged in the account's .php.error.log:

PHP Deprecated:  session_set_save_handler(): Providing individual callbacks instead of an object implementing SessionHandlerInterface is deprecated in /usr/local/cpanel/base/3rdparty/roundcube/program/lib/Roundcube/rcube_session.php on line 119

Description

The warnings can be safely ignored and do not cause any issues with Roundcube or cPanel.

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-50514. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

No workaround is available at this time.