WordPress blank screen after saving/logging

Hi all,

I’m getting the white screen of death every time I try to access wordpress control panel. The problem gets kind of fixed when I rename my custom theme folder and then rename it back to its original name via ftp, since I get access to wordpress by doing so, but then everytime I click on save changes in entries/pages, I get the white screen again, eventhough changes are saved. Also, when I log out and then log in, the problem appears again and I have to do the renaming thing to fix it.

Things I have done so far:

wp-config and wp-functions files have ?> closed and no blank space on top or at the end.

I have renamed the plugin folder to plugins_old so plugins don’t work. White screen still appearing.

debugging says (I translate it since I have it in spanish):

Error calling main_sidebar, undefined ID for main_sidebar -> That, I already fixed it by putting ‘id’ => ‘sidebar-1’ in the array inside functions.php

Then there is this one:

PHP Notice: Undefined index: no_post_titles in …/wordpress/wp-content/plugins/list-category-posts/include/lcp-catlistdisplayer.php on line 234 [06-May-2015 07:13:38 UTC] PHP Notice: Undefined index: no_post_titles in

I copy and paste that line of code:

if ( empty($this->params['no_post_titles']) || !empty($this->params['no_post_titles']) && $this->params['no_post_titles'] !== 'yes' ) {
  $lcp_display_output .= $this->get_post_title($single);
}

Anyway, I have disabled the list category post plugin, white screen still showing up.

Any help please?