Codeigniter not showing helpful error messgaes

The error is clear. You are passing a resource type as the first parameter of htmlspecialchars, which usually accepts a string. Please check the variable you are passing to the first param.

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Ok. Scrap my last comment. The error is from the built in error exception file.

Do you have somewhere in your code that you defined a constant equivalent to a resource? Something like define('STREAM', STDOUT); or define('MY_FILE', fopen('path/to/file', 'rb'));

The problem is that the file is printing all defined constants and escaping them using htmlspecialchars. But somewhere a user defined constant is set to a resource so this causes a fatal error.