cPanel are upgrading the embedded version of perl on cPanel v11.56 (v56) from perl v5.14 to v5.22, which is a good thing. However, any daemons running under the cPanel embedded version of perl must be restarted after cPanel upgrades otherwise they will start to fail with obscure messages.
To avoid this, you should ensure that any such daemon processes are restarted soon after the upgrade to cPanel v11.56. In the case of ConfigServer products, this means: lfd, cxs and MailScanner.
Fortunately, if you are running csf/lfd on your server then lfd automatically does this for you (for lfd, cxs and MailScanner) whenever upcp runs and upgrades the cPanel version, so you should not need to do anything.
However, if you do have problems or you do not run csf/lfd but do use MailScanner or cxs, then you will need to restart those services manually once your installation of cPanel upgrades to this new release.