You receive an email stating:
Error: An Error Occurred While Processing This Directive
This is the most generic error message in cPanel. You might see this when a user account loads the cPanel main screen, or you might see it when performing any particular function in WHM. Fortunately, it's probably the easiest to diagnose and fix.
Look at the logs
You'll need to login to the server as root via SSH. You'll need to scan the cPanel error log for errors. You can usually use 'tail' to get the most recent error.
tail -n 20 /usr/local/cpanel/logs/error_log
You'll be looking for a line similar to:
Can't locate Class/Std.pm in @INC (@INC contains: /usr/local/cpanel /usr/lib/perl5/5.8.7/x86_64-linux /usr/lib/perl5/5.8.7 /usr/lib/perl5/site_perl/5.8.7/x86_64-linux /usr/lib/perl5/site_perl/5.8.7 /usr/lib/perl5/site_perl/5.8.5 /usr/lib/perl5/site_perl/5.8.4 /usr/lib/perl5/site_perl/5.8.3 /usr/lib/perl5/site_perl/5.8.2 /usr/lib/perl5/site_perl/5.8.1 /usr/lib/perl5/site_perl/5.8.0 /usr/lib/perl5/site_perl .) at /usr/local/cpanel/Cpanel/Lang/Cache/Utils.pm line 11
That first bit, Can't Locate Class/Std.pm is the key; It's missing the 'Class::Std Perl module'
Now you type:
You can also use WHM to install Perl Modules, by going to Software and then Install a Perl Module.
Once it's completed, then try your cPanel/WHM functions again. If you still receive the error, then you'll need to look for other Perl modules in the cPanel error_log and reinstall those too.
Lather, rinse, repeat