In admin panel homepage, when I click on any order from the "Last 5 orders" section I get a 500 error.
I have tried reading var/log/system.log, and below is the log that was created when I encounter that 500 error.
Warning: include(): Failed opening 'Mage/Customer/Model/Attribute.php' for inclusion (include_path='/home/xxx/public_html/app/code/local:/home/xxx/public_html/app/code/community:/home/xxx/public_html/app/code/core:/home/xxx/public_html/lib:.:/opt/cpanel/ea-php56/root/usr/share/pear') in /home/xxx/public_html/lib/Varien/Autoload.php on line 94
Is there anything I could do to resolve or identify the root cause of this issue?