Error should be like this.
Uncaught TypeError: Argument 1 passed to CI_Exceptions::show_exception() must be an instance of Exception, instance of Error given, called in /your/project/system/core/Common.php on line 658 and defined in /your/project/system/core/Exceptions.php:190 Stack trace:
Step 1: Download the latest codeigniter version(Codeigniter 3.1.2)
Step 2: Copy the ‘system’ folder from newly download Codeigniter project and replace the existing Codeigntier 3.0.0 project’s system folder.