The reason for this issue due to missing some lines in httpd.conf.
Fix
====
1) Open the apache configuration file(httpd.conf) in your favorite editor.
2) Add the following lines in the httpd.conf.
===================================================================
ErrorDocument 400 /400.shtml
ErrorDocument 401 /401.shtml
ErrorDocument 403 /403.shtml
ErrorDocument 404 /404.shtml
ErrorDocument 500 /500.shtml
ScriptAlias /cgi-sys/ /usr/local/cpanel/cgi-sys/ Alias /sys_cpanel/ /usr/local/cpanel/sys_cpanel/ Alias /java-sys/ /usr/local/cpanel/java-sys/ Alias /img-sys/ /usr/local/cpanel/img-sys/ Alias /akopia/ /usr/local/cpanel/3rdparty/interchange/share/akopia/
Alias /neo-images/ /usr/local/cpanel/base/neomail/neo-images/
ScriptAliasMatch ^/cpanel/(.*) /usr/local/cpanel/cgi-sys/redirect.cgi
ScriptAlias /cpanel /usr/local/cpanel/cgi-sys/redirect.cgi
ScriptAlias /whm /usr/local/cpanel/cgi-sys/whmredirect.cgi
ScriptAlias /securewhm /usr/local/cpanel/cgi-sys/swhmredirect.cgi
ScriptAlias /webmail /usr/local/cpanel/cgi-sys/wredirect.cgi
ScriptAliasMatch ^/webmail/(.*) /usr/local/cpanel/cgi-sys/wredirect.cgi
ScriptAliasMatch ^/kpanel/(.*) /usr/local/cpanel/cgi-sys/redirect.cgi
ScriptAlias /controlpanel /usr/local/cpanel/cgi-sys/redirect.cgi
ScriptAlias /securecontrolpanel /usr/local/cpanel/cgi-sys/sredirect.cgi
Alias /mailman/archives/ /usr/local/cpanel/3rdparty/mailman/archives/public/
ScriptAlias /mailman/ /usr/local/cpanel/3rdparty/mailman/cgi-bin/
Alias /pipermail/ /usr/local/cpanel/3rdparty/mailman/archives/public/
Alias /interchange/ /usr/local/cpanel/3rdparty/interchange/share/interchange/
Alias /interchange-5/ /usr/local/cpanel/3rdparty/interchange/share/interchange-5/
===================================================================
3) Now restart the httpd service in the server.