Server Error when trying to access AdminCP

[Jeffin]

I just cleaning up my public_html folder of unwanted files and folders like my previous vbulletin files etc. In the process, I think I deleted some xenforo dependent files too like addons. I am not sure but I now get the below error when I try and access the admin control panel:

Server Error

fopen(/home/--------/public_html/internal_data/install-lock.php) [function.fopen]: failed to open stream: Permission denied

XenForo_Application::handlePhpError() in XenForo/Install/Model/Install.php at line 270
XenForo_Install_Model_Install->writeInstallLock() in XenForo/ControllerAdmin/Abstract.php at line 94
XenForo_ControllerAdmin_Abstract->_assertInstallLocked() in XenForo/ControllerAdmin/Abstract.php at line 16
XenForo_ControllerAdmin_Abstract->_preDispatchType() in XenForo/Controller.php at line 302
XenForo_Controller->preDispatch() in XenForo/FrontController.php at line 309
XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 132
XenForo_FrontController->run() in /home/jeffinj/public_html/admin.php at line 13

Would anyone know what might have gone wrong? I have re-uploaded all original xf files and the site is still working except accessing the control panel shows the errors.

 

[Jeffin]

Update:

Looks like I was able to resolve the issue myself.

 

[Jake Bunce]

data and internal_data should be fully writable (chmod 777, or maybe 755 depending on your server config).