The cpanel 11 requires perl version  5.8.8. To upgrade the perl version in the server you can use following steps:-

1. Download perl 5.8.8 using following link:-

    [root@serv ~]# wget http://layer1.cpanel.net/perl588installer.tar.gz

2. Untar the tar package using following command

 [root@serv ~]# tar -vzxf perl588installer.tar.gz

3. Then Install

 [root@serv ~]# cd perl588installer
  [root@serv ~]# ./install

Once this has completed, execute the following to ensure that all modules
required by cPanel are installed, and restart cPanel:

   [root@serv ~]# /usr/local/cpanel/bin/checkperlmodules
  [root@serv ~]# /usr/local/cpanel/startup

4. Check and confirm the perl version using the command:

 [root@serv ~]# perl -v