I encountered the following error while restarting spamassassin.
Starting spamd: Feb 21 20:29:26.275  warn: Argument “” isn’t numeric in addition (+) at /usr/local/lib/perl5/site_perl/5.8.8/Mail/SpamAssassin/NetSet.pm line 122.
Feb 21 20:29:26.276  warn: oops! unparseable IPv6 address for 127/8: 168355856 at /usr/local/lib/perl5/site_perl/5.8.8/Mail/SpamAssassin/NetSet.pm line 128.
Feb 21 20:29:26.276  warn: oops! unparseable IPv6 address for 127/8: 168356228 at /usr/local/lib/perl5/site_perl/5.8.8/Mail/SpamAssassin/NetSet.pm line 128.
child process  exited or timed out without signaling production of a PID file: exit 255 at /usr/bin/spamd line 2582.
The work around I found is to change cpanel to stable version and run upcp.
then do this,
sa-learn -D –force-expire
This should fix the issue.