Fatal error when attaching PDF

Hi,

I use a ticketing plugin and whenever I enable sending the PDF ticket via email, my site crashes and WordPress sends me this error.

Error Details =============

An error of type E_ERROR was caused in line 515 of the file /<<plugin directory>>/post-smtp/Postman/Postman-Mail/PostmanMessage.php.

Error message:

Uncaught ValueError: file_get_contents(): Argument #1 ($filename) must not contain any null bytes in /<<plugin directory>>/post-smtp/Postman/Postman-Mail/PostmanMessage.php:515

Stack trace:

0 /<<plugin directory>>/post-smtp/Postman/Postman-Mail/PostmanMessage.php(515): file_get_contents('%PDF-1.7\n%\xE2\xE3\xCF\xD3\n…’)

1 /<<plugin directory>>/post-smtp/Postman/Postman-Mail/PostmanZendMailEngine.php(186): PostmanMessage->addAttachmentsToMail(Object(Postman_Zend_Mail))

2 /<<plugin directory>>/post-smtp/Postman/PostmanWpMail.php(236): PostmanZendMailEngine->send(Object(PostmanMessage))

3 /<<plugin directory>>/post-smtp/Postman/PostmanWpMail.php(60): PostmanWpMail->sendMessage(Object(PostmanMessage), Object(PostmanEmailLog))

4 /<<plugin directory>>/post-smtp/Postman/PostmanWpMailBinder.php(121): PostmanWpMail->send('me@doyenwilliam…', 'Your ticket is …', 'Hello the D'…', '', Array)

5 /<<plugin directory>>/tickera/includes/general-functions.php(1116): wp_mail('me@doyenwilliam…', 'Your ticket is …', 'Hello the D'…', '', Array)

6 /<<plugin directory>>/tickera/includes/general-functions.php(1039): tc_order_paid_attendee_email(2026)

7 /<<WP directory>>/wp-includes/class-wp-hook.php(308): tc_maybe_send_order_paid_attendee_email(Object(WC_Order))

8 /<<WP directory>>/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)

9 /<<WP directory>>/wp-includes/plugin.php(517): WP_Hook->do_action(Array)

10 /<<plugin directory>>/bridge-for-woocommerce/bridge-for-woocommerce.php(1724): do_action('tc_wb_allowed_t…', Object(WC_Order))

11 /<<WP directory>>/wp-includes/class-wp-hook.php(310): TC_WooCommerce_Bridge->check_tickets_action(2026, 'processing', 'completed’)

12 /<<WP directory>>/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)

13 /<<WP directory>>/wp-includes/plugin.php(517): WP_Hook->do_action(Array)

14 /<<plugin directory>>/woocommerce/includes/class-wc-order.php(397): do_action('woocommerce_ord…', 2026, 'processing', 'completed', Object(Automattic\WooCommerce\Admin\Overrides\Order))

15 /<<plugin directory>>/woocommerce/includes/class-wc-order.php(245): WC_Order->status_transition()

16 /<<plugin directory>>/woocommerce/includes/admin/meta-boxes/class-wc-meta-box-order-data.php(699): WC_Order->save()

17 /<<WP directory>>/wp-includes/class-wp-hook.php(310): WC_Meta_Box_Order_Data::save(2026)

18 /<<WP directory>>/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)

19 /<<WP directory>>/wp-includes/plugin.php(517): WP_Hook->do_action(Array)

20 /<<plugin directory>>/woocommerce/includes/admin/class-wc-admin-meta-boxes.php(258): do_action('woocommerce_pro…', 2026, Object(WP_Post))

21 /<<WP directory>>/wp-includes/class-wp-hook.php(310): WC_Admin_Meta_Boxes->save_meta_boxes(2026, Object(WP_Post))

22 /<<WP directory>>/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)

23 /<<WP directory>>/wp-includes/plugin.php(517): WP_Hook->do_action(Array)

24 /<<WP directory>>/wp-includes/post.php(4715): do_action('save_post', 2026, Object(WP_Post), true)

25 /<<WP directory>>/wp-includes/post.php(4817): wp_insert_post(Array, false, true)

26 /<<WP directory>>/wp-admin/includes/post.php(439): wp_update_post(Array)

27 /<<WP directory>>/wp-admin/post.php(227): edit_post()

28 {main} thrown