If you see such an error message after logging into cPanel, it says something is broken with the cPanel system. First step you should do is to take a look into the cPanel error log. An eaiest way to do this is, run the following command in command line and reload the WHM/cPanel inteface; that will show you the latest errors while loading the panel.
tail -f /usr/local/cpanel/logs/error_log
Once the error is identified, you may take corrective actions and fix errors. Many errors can be fixed by running a cPanel update, but sometime it needs additional troubleshooting steps.
For example, a sample error we were facing with one of the servers is following.
/usr/local/cpanel/whostmgr/bin/whostmgr: error while loading shared libraries: /usr/local/cpanel/3rdparty/perl/514/lib64/perl5/cpanel_lib/x86_64-linux-64int/auto/Cpanel/Optimizer/Optimizer.so: cannot open shared object file: No such file or directory
Duplicate logaccess: at /usr/local/cpanel/Cpanel/Server.pm line 421.
Cpanel::Server::logaccess(Cpanel::Server=HASH(0x380aed0)) called at /usr/local/cpanel/Cpanel/Server.pm line 365
Cpanel::Server::body_internal_error(Cpanel::Server=HASH(0x380aed0), 500, “No response from subprocess (whostmgr (whostmgr)): The subpro”…) called at /usr/local/cpanel/Cpanel/Server.pm line 313
The error states, there is a missing library for whostmgr binary. We fixed the above error by running the following commands