When clicking Download I get error “Function get_cart was called incorrectly”

Hey,
last week everything was still working. I have WPDM installed to protect downloads in my LearnDash courses that I sell via Woocommerce. Today when clicking Download I get the error message, it just keeps repeating on the entire page but I could not copy it out of there for some reason so I typed it:

“Notice: Function get_cart was called incorrectly. Get cart should not be called before the wp_loaded action. Backtrace: require(‘wp-blog-header.php’), require_once(‘wp-load.php’), require_once(‘wp-config.php’), require_once(wp-settings.php’), do_action(‘init’), WP_Hook->do_action, WP_Hook->apply_filters, WPDM\__\Apply->triggerDownload, include(‘/plugins/download-manager/src/wpdm-start-download.php’), WPDM\__\Messages:fullPage, include(‘plugins/download-manager/src/__/views/message.php’),wp_head,do_action(‘wp_head’),WP_Hook->do_action,WP_Hook->apply_filters,wp_enqueue_scripts,do_action(‘wp_enqueue_scripts’),QP_Hook->do_action,WP_Hook->apply_filters,WC_Payment_Gateway_WCPay->register_scripts_for_zero_order_total,WC_Cart->is_empty,WC_Cart->get_cart,wc_doing_it_wrong Please see Debugging in WordPress for more information. (This message was added in version 2.3) in …/functions.php on line 5835”

Somewhere hidden in all the Notices it says “Sorry, file not found!”

Does anyone have an idea how to fix this?

Did you get my private message?

Hey, sorry I was sleeping. In the meantime I actually deactivated ALL other plugins and the error still persists. However, I also have the same issue with the Download Monitor plugin. I even deleted all other plugins and switched to the 2020 theme.
Something seems seriously broken with my page, do you have any idea how to fix it?

Thank you so much, such a simple problem. Apparently, when I rolled back the backup it messed up the file links internally.