WooCommerce PDF Invoices, Packing Slips and Credit Notes Plugin – Troubleshooting Guide

This issue mainly occurs due to the following reasons:

1. Lack of an image processing library

If an image processing library is absent or incompatible with the uploaded image, it may result in missing or corrupted images in the PDF.

Solution

Make sure to use an image processing library that is compatible with the uploaded images.

2. Image size

Uploading images that exceed the server capacity can lead to image-missing issues.

Solution

Make sure to upload images that fit within the server’s capacity.

3. Server request restrictions

When your site’s images are hosted on an external server, there is a possibility that the server may block requests from external servers.

Solution

Contact your server team to identify and resolve any restrictions blocking external server requests.

4. Permission issues

Insufficient file permissions can prevent WordPress from accessing and displaying images stored on the hosting server, leading to missing or corrupted images in PDFs.

Solution

Ensure that WordPress has the required file permissions to read and process images on the hosting server.

5. Issue with the dompdf library

The plugin uses the built-in Dompdf library, which may not support certain image formats when converting HTML to PDF. This can result in missing images in the generated PDF documents.

Solution

Replace the Dompdf library with the Mpdf library using WebToffee’s free mPDF add-on. Follow these steps:

1. Install and activate WebToffee’s free mPDF add-on.
2. Navigate to Invoice/Packing > General Settings > Advanced.
3. Under PDF library, select Mpdf.
4. Click on Update Settings.

To learn more, check out the following article: Fix Image/Logo Missing Issues.

The built-in Dompdf library struggles to handle certain languages, particularly RTL (Right-to-Left) languages like Arabic and Hebrew, which can cause text to appear incorrectly in PDF documents.

Solution

To resolve this issue, install WebToffee’s free mPDF add-on, enable RTL support, and replace the Dompdf library with mPDF. Follow these steps:

1. Install and activate WebToffee’s free mPDF add-on.
2. Navigate to Invoice/Packing > General Settings > Advanced.
3. Enable RTL support for documents.
4. Under the PDF library option, select Mpdf.
5. Click on Update Settings.

To learn more, check out the following article: Fix Language Missing Issue.

This issue often occurs due to a firewall installed on your website. Firewalls like WordFence and Sucuri may block the actions required to save the plugin settings, preventing changes from being applied.

Workaround

Whitelist the blocked action to allow settings to be saved. Admins can allow certain actions by adding them to the whitelist.

The plugin supports popular translation tools like WPML String Translation and Loco Translate, which help translate strings within the plugin. However, when using WPML String Translation, some strings may not appear for translation.

Solution

To make the missing strings available for translation in WPML, follow these steps:

1. From the WordPress dashboard, navigate to WPML > String Translation.
2. Enable the ‘Look for strings while pages are rendered’ option.

3. Navigate to WooCommerce > Orders and generate an invoice (if the missing strings are in the invoice document).
4. Return to WPML > String Translation, where the previously missing strings will now appear.
5. Add translations for the newly detected strings.
6. Finally, disable the ‘Look for strings while pages are rendered’ option.