If you receive an “Internal Death” (generic cPanel speak for “something broke”) when accessing WHM and/or cPanel, the first thing you should do is check the cPanel error logs at /usr/local/cpanel/logs/error_log. You may see something like this:
die [Internal Death while parsing [stdin] xxxxx] Read of CDB_File failed: Protocol error at /usr/local/cpanel/Cpanel/CPAN/Locale/Maketext.pm line 217.
Cpanel::CPAN::Locale::Maketext::maketext() called at /usr/local/cpanel/whostmgr/docroot/templates/menu/root.tmpl line 53
This is almost always an issue with the locale database, and tends to occur when a cPanel update failed due to outside conditions – such as a server running of our disk space, memory, etc during the update. To fix this, simply move the locale files out of the way:
mv /var/cpanel/locale /var/cpanel/bad_locale
If you have custom locales installed, you can go ahead and move the files back in (unless, of course, the custom locales were what was causing the problem).
If your cPanel update did indeed fail, it’s a good idea to run it again.