这是CodeIgniter 3.0.0中的一个已知问题，请参阅github问题此处和 changelog 以下：

PHP 7下的新错误异常的错误处理（＃4137） - ：doc：错误处理< general / errors> 。

这是因为set_exception_handler（）
$ b $ b set_exception_handler（）使用Exception的类型声明，
会在抛出Error对象时导致致命错误。

如果处理程序需要同时工作PHP 5和7，你应该从处理程序中删除
类型声明，而正在执行
的代码只能通过Throwable替换为Exception
类型声明。

 <？php 
 // PHP 5时代代码会破解。 
 function handler（Exception $ e）{...} 
 set_exception_handler（'handler'）; 

 // PHP 5和7兼容。 
 function handler（$ e）{...} 

 //仅限PHP 7。 
 function handler（Throwable $ e）{...} 
？> 
 

升级到3.0.2以外的任何版本都能解决您的问题。 / p>

I was using CodeIgniter 3.0.0 with PHP 5.6.

Yesterday I updated to PHP 7 and started getting following error:-

Uncaught TypeError: Argument 1 passed to CI_Exceptions::show_exception() must be
 an instance of Exception, instance of Error given, called in /my/file/path/app/system/core/Common.php on line 658 and defined in /my/file/path/hgx_portal/app/system/core/Exceptions.php:190
Stack trace:
#0 /my/file/path/hgx_portal/app/system/core/Common.php(658): CI_Exceptions->show_exception(Object
(Error))
#1 [internal function]: _exception_handler(Object(Error))
#2 {main}
  thrown in /my/file/path/hgx_portal/app/system/core/Exceptions.phpon line 190

This is a know issue in CodeIgniter 3.0.0, see the github issue here and changelog below:

Fixed a bug (#4137) - :doc:Error Handling <general/errors> breaks for the new Error exceptions under PHP 7.

It's because set_exception_handler() changed behavior in PHP 7.

Code that implements an exception handler registered with set_exception_handler() using a type declaration of Exception will cause a fatal error when an Error object is thrown.

If the handler needs to work on both PHP 5 and 7, you should remove the type declaration from the handler, while code that is being migrated to work on PHP 7 exclusively can simply replace the Exception type declaration with Throwable instead.

<?php
// PHP 5 era code that will break.
function handler(Exception $e) { ... }
set_exception_handler('handler');

// PHP 5 and 7 compatible.
function handler($e) { ... }

// PHP 7 only.
function handler(Throwable $e) { ... }
?>

Upgrading to anything beyond 3.0.2 will fix your issue.