Fatal error: ob_start() [ref.outcontrol]: Cannot use output buffering in output buffering display handlers in /home/.../public_html/system/codeigniter/system/core/Exceptions.php on line 166

Unfortunately the web server to my site was hacked and an add-on designed for the control panel had code inserted into one of it's files. I have removed the offending file and ensured that my server settings were secure. Unfortunately, in the process aspects of that plugin are not working. I attempted to manually remove the add-on by removing references to it within the database.

This did resolve the original error that I was receiving. However, I am now receiving a new error as noted above. I have checked and even replaced the entire codeigniter directory, so there is no malicious code within it.

At this point the website is rendering correctly, but the admin.php is still displaying the above error. I assume that it has something to do with what i did in the sql database, but I am unsure how to track down and repair this issue. Any assistance would be appreciated.

2 Answers 2


That's a nasty one to debug. My advice is to let someone with a bit of codeigniter / expressionengine knowhow look at.

If the addon was an extension, check if it is still referenced in the exp_extensions table. (duplicate table first as backup, then remove row with offending extension from exp_extensions table).

edit: you might also be able to disable all extension in config (without unstalling them).
See this SE topic. Is there a quick way to disable all plugins?


Try setting this line in config.php to be FALSE:

$config['compress_output'] = FALSE; 

When I see an error, I go to the line of code to see what the script is trying to do. Line 166 in the /system/codeigniter/system/core/Exceptions.php file is in the show_php_error() function so I'd suggest checking your PHP error logs to see what error is being thrown. If no error is being logged in the error file, go into the CP index.php file and remove the conditional around the error logging to force it to log the error and reload your problem page.

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