WordPress Backup fails: “Access level to ElementorProModulesThemeBuilderDocumentsTheme_Document::get_create_url() must be public”

Symptoms

• WordPress Backup process fails with the following error:

  Failed to restore the extension wp-toolkit: Failed to reset cache for the instance #1: PHP Fatal error: Access level to ElementorProModulesThemeBuilderDocumentsTheme_Document::get_create_url() must be public (as in class ElementorCoreBaseDocument) in /var/www/vhosts/example.com/httpdocs/wp-content/plugins/elementor-pro/modules/theme-builder/documents/theme-document.php on line 123

• Elementor Pro plugin is not updated to the latest version.

Cause

The issue is caused by outdated plugin Elementor Pro.

Resolution

Update Elementor Pro Plugin to the latest version:

1. Log in to Plesk.
2. Go to WordPress > example.com > Plugins and update Elementor Pro plugin.