Elementor “core” fatal error

Hello,
I have enjoyed using Elementor but now I’m getting an error that includes the word “core”. I am also getting a warning on my WP Securi dashboard saying “Core WordPress Files were modified”. I sure didn’t modify them. I have a pretty basic website and I don’t do anything but update the 4 plugins I have. I updated everything September 3rd and that’s when the trouble began. I have since gone back to a previous backup and things were working ok until I got an e-mail from WP telling me about my Elementor error. So I guess things aren’t working after all.

My other plugins are: MailChimp, Metaslider, NextGEN gallery and Askimet Anti-spam and Gravity Forms.

The e-mail I got from WP says this:
First, visit your website (https://joanbreckwoldt.com/) and check for any visible issues. Next, visit the page where the error was caught (https://joanbreckwoldt.com/wp-admin/admin-ajax.php) and check for any visible issues.

That page they refer to shows nothing but white. (Not very helpful to me!)

I put my website in the box above, though the specific page is mentioned above.

THANK YOU so much in advance for any help you can give me.

Joan

This was also included in the e-mail: When seeking help with this issue, you may be asked for some of the following information:
WordPress version 5.5.1
Current theme: Maryline (pipdig) (version 2.3.5)
Current plugin: Elementor (version 2.9.14)
PHP version 7.3.12

The update is what I believe caused this problem on Sept. 3rd which is why you will see I don’t have the current update of Elementor. I reverted to a back up on Sept. 2nd. The day before I updated. But, as I mentioned, now I have a seemingly more serious problem. (I didn’t get an e-mail before).

Error Details
=============
An error of type E_ERROR was caused in line 131 of the file /var/www/wp-content/plugins/elementor/includes/autoloader.php. Error message: Uncaught Error: Class ‘Elementor\Controls_Manager’ not found in /var/www/wp-content/plugins/elementor/includes/autoloader.php:131
Stack trace:
#0 /var/www/wp-content/plugins/elementor/includes/autoloader.php(78): Elementor\Autoloader::init_classes_map()
#1 /var/www/wp-content/plugins/elementor/includes/autoloader.php(251): Elementor\Autoloader::get_classes_map()
#2 /var/www/wp-content/plugins/elementor/includes/autoloader.php(304): Elementor\Autoloader::load_class(‘Core\\Logger\\Man…’)
#3 [internal function]: Elementor\Autoloader::autoload(‘Elementor\\Core\\…’)
#4 /var/www/wp-content/plugins/elementor/includes/plugin.php(663): spl_autoload_call(‘Elementor\\Core\\…’)
#5 /var/www/wp-content/plugins/elementor/includes/plugin.php(472): Elementor\Plugin->__construct()
#6 /var/www/wp-content/plugins/elementor/includes/plugin.php(679): Elementor\Plugin::instance()
#7 /var/www/wp-content/plugins/elementor/elementor.php(54): require(‘/var/www/wp-con…’)
#8 /var/www/wp-settings.php(377): include_once(‘/var/www/w

The page I need help with: [log in to see the link]