Submitting form causes internal server rror

When submitting a form with CF7 5.4 it returns error:

Fatal error: Uncaught Error: Call to private method WPCF7_Submission::add_uploaded_file() from context '' in /var/www/html/wp-content/plugins/multiline-files-for-contact-form-7/multiline-files-upload-for-contact-form-7.php:467 Stack trace: #0 /var/www/html/wp-includes/class-wp-hook.php(287): mfcf7_zl_multilinefile_validation_filter(Object(WPCF7_Validation), Object(WPCF7_FormTag)) #1 /var/www/html/wp-includes/plugin.php(206): WP_Hook->apply_filters(Object(WPCF7_Validation), Array) #2 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(365): apply_filters('wpcf7_validate_...', Object(WPCF7_Validation), Object(WPCF7_FormTag)) #3 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(59): WPCF7_Submission->validate() #4 /var/www/html/wp-content/plugins/contact-form-7/includes/submission.php(24): WPCF7_Submission->proceed() #5 /var/www/html/wp-content/plugins/contact-form-7/includes/contact-form.php(763): WPCF7_Submission::get_instance(Object(WPCF7_ContactForm), Array) #6 /var/www/html/wp-c in /var/www/html/wp-content/plugins/multiline-files-for-contact-form-7/multiline-files-upload-for-contact-form-7.php on line 467