I use codeigniter in my blog and since a while I get this error
PHP Fatal error: Call to a member function append_output() on a non-object in /var/www/site/blog/system/core/Loader.php on line 862
I don't know what change caused this and why it appears. The site gets rendered and send to browser completely, from views header.php, index.php to footer.php everything is there and after that this error appears. Search with google showed another site, that has this error at the very bottom of their site...
I now supressed the error with error_reporting(0) as the whole site works fine, but that's not a solution I want to stay with.
It happens on all pages, I have one Controler (blog.php) and several methods like index(), article(), archive() in it. The methods do what they are supposed to do, but when CI finished rendering the page, the error appears, with all controler methods.
What can I do to trace where this problem appears?
https://github.com/EllisLab/CodeIgniter/blob/develop/system/core/Loader.php#L938 If the error is occurring on the value returned from get_instance, here will be your problem. Although you may have to look at the version you are using to get the right line number.
Additionally: https://github.com/EllisLab/CodeIgniter/blob/develop/system/core/Controller.php#L75
This appears to be the singleton class that function leads to, it is returning self::$instance which is created in the constructor.
To me this means the CI_Controller singleton has not been instantiated at the time that error has occurred.
Hope that helps you debug your problem.
I had the same problem. I'd overwritten the output class ($this->output) in my controller.