I can reproduce the problem:
PHP Fatal error: Uncaught Error: Call to private method WPCF7_Submission::add_uploaded_file() from context 'WPCF7_Pdf_Forms' in /var/www/html/wp-content/plugins/pdf-forms-for-contact-form-7/pdf-forms-for-contact-form-7.php:968
Stack trace:
#0 /var/www/html/wp-includes/class-wp-hook.php(287): WPCF7_Pdf_Forms->fill_and_attach_pdfs(Object(WPCF7_ContactForm), false, Object(WPCF7_Submission))
#1 /var/www/html/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array)
#2 /var/www/html/wp-includes/plugin.php(551): WP_Hook->do_action(Array)
#3 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(457): do_action_ref_array('wpcf7_before_se...', Array)
#4 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(80): WPCF7_Submission->before_send_mail()
#5 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(24): WPCF7_Submission->proceed()
#6 /var/www/html/wp-content/plugins/contact-form-7/includes/contact-form.php(763): WPCF7_Submission::get_instance(Object(WPCF7_Contact in /var/www/html/wp-content/plugins/pdf-forms-for-contact-form-7/pdf-forms-for-contact-form-7.php on line 968
Please downgrade to the previous version of Contact Form 7. I will try to come up with a fix as soon as possible.