Permission denied on admin.php

Hello all,

I am experiencing the infamous “You do not have sufficient permissions to access this page.” error when trying to access /wp-admin/admin.php?page=thesis-options while logged in as any administrator user.

I have recently upgraded the core and all plugins, removed some backdoors and a lot of spam from the blog posts, renamed table prefixes and moved to a new server.

The server is a VPS running Ubuntu with Nginx.

I have tried the following things to try and get access to this page with no success:

• forcing db update by changing db_version value
• checked and rechecked prefixes for table names, options and usermeta
• changed table prefixes back to original
• change usermeta capabilities value to both a:1:{s:13:”administrator”;b:1;} and a:1:{s:13:”administrator”;s:1:”1″;}
• deactivating all plugins
• set standard wp user roles in options table wp_user_roles
• use simpler table prefix (just lower case letters and underscores)
• change auth keys and salts
  forced wp upgrade with this script: https://markjaquith.wordpress.com/2006/03/28/wordpress-error-you-do-not-have-sufficient-permissions-to-access-this-page
• (the script threw a 500)
• change theme to Twenty Fifteen
• redownloaded and overwritten wp-includes and wp-admin

I added the below code to wp-admin/menu.php:

if ( !user_can_access_admin_page() ) {
    $a = array(
        'Pages No Access' => $_wp_menu_nopriv,
        'User Info' => $current_user,
        'Roles' => $wp_roles->get_names(),
    );
    $s = sprintf("\n<br /><pre>%s</pre>", print_r($a, true));
    do_action('admin_page_access_denied');
    wp_die( __('You do not have sufficient permissions to access this page.'.$s) );
}

Which yielded the following:

Array

(

    [Pages No Access] => 

    [User Info] => WP_User Object

        (

            [data] => stdClass Object

                (

                    [ID] => 251

                    [user_login] => maxmumford

                    [user_pass] => ********

                    [user_nicename] => maxmumford

                    [user_email] => ********

                    [user_url] => http://www.cocept.io

                    [user_registered] => 2016-03-29 13:43:32

                    [user_activation_key] => ********

                    [user_status] => 0

                    [display_name] => Max Mumford

                )

            [ID] => 251

            [caps] => Array

                (

                    [administrator] => 1

                )

            [cap_key] => wp_capabilities

            [roles] => Array

                (

                    [0] => administrator

                )

            [allcaps] => Array

                (

                    [switch_themes] => 1

                    [edit_themes] => 1

                    [activate_plugins] => 1

                    [edit_plugins] => 1

                    [edit_users] => 1

                    [edit_files] => 1

                    [manage_options] => 1

                    [moderate_comments] => 1

                    [manage_categories] => 1

                    [manage_links] => 1

                    [upload_files] => 1

                    [import] => 1

                    [unfiltered_html] => 1

                    [edit_posts] => 1

                    [edit_others_posts] => 1

                    [edit_published_posts] => 1

                    [publish_posts] => 1

                    [edit_pages] => 1

                    [read] => 1

                    [level_10] => 1

                    [level_9] => 1

                    [level_8] => 1

                    [level_7] => 1

                    [level_6] => 1

                    [level_5] => 1

                    [level_4] => 1

                    [level_3] => 1

                    [level_2] => 1

                    [level_1] => 1

                    [level_0] => 1

                    [edit_others_pages] => 1

                    [edit_published_pages] => 1

                    [publish_pages] => 1

                    [delete_pages] => 1

                    [delete_others_pages] => 1

                    [delete_published_pages] => 1

                    [delete_posts] => 1

                    [delete_others_posts] => 1

                    [delete_published_posts] => 1

                    [delete_private_posts] => 1

                    [edit_private_posts] => 1

                    [read_private_posts] => 1

                    [delete_private_pages] => 1

                    [edit_private_pages] => 1

                    [read_private_pages] => 1

                    [delete_users] => 1

                    [create_users] => 1

                    [unfiltered_upload] => 1

                    [edit_dashboard] => 1

                    [update_plugins] => 1

                    [delete_plugins] => 1

                    [install_plugins] => 1

                    [update_themes] => 1

                    [install_themes] => 1

                    [update_core] => 1

                    [list_users] => 1

                    [remove_users] => 1

                    [promote_users] => 1

                    [edit_theme_options] => 1

                    [delete_themes] => 1

                    [export] => 1

                    [wysija_newsletters] => 1

                    [wysija_subscribers] => 1

                    [wysija_subscriwidget] => 1

                    [wysija_config] => 1

                    [wysija_theme_tab] => 1

                    [wysija_style_tab] => 1

                    [wysija_stats_dashboard] => 1

                    [administrator] => 1

                )

            [filter] => 

        )

    [Roles] => Array

        (

            [administrator] => Administrator

            [editor] => Editor

            [author] => Author

            [contributor] => Contributor

            [subscriber] => Subscriber

        )

)

From which we can see that my user has the appropriate permission and the user roles settings are intact.

I am pretty stumped… I seem to have exhausted Google and can’t think of anything else. Can somebody help?