WHMCS Custom PDF Invoice Addon

Requirements

• WHMCS with administrator access to addon-module configuration.
• A compatible ionCube Loader v14 and above when the supplied PHP files are ionCube encoded.
• PHP cURL and OpenSSL for license verification and encrypted license-key handling.
• PHP GD for logo, signature, round stamp, watermark, background, header, and footer image processing.
• PHP JSON and mbstring extensions.
• A valid PDF Invoice license key issued by WHMCSModule Networks.

Before installation, back up the WHMCS database and the active template's invoicepdf.tpl and quotepdf.tpl files.

Fresh installation

1. Upload the complete PDFInvoice directory to:

   /path/to/whmcs/modules/addons/PDFInvoice

   The directory name is case-sensitive on Linux and must remain PDFInvoice.

2. Confirm that the following file exists:

   /path/to/whmcs/modules/addons/PDFInvoice/PDFInvoice.php

3. In WHMCS, open System Settings > Addon Modules.

4. Locate PDF Invoice and select Activate.

5. Enter the license key in the module configuration and save it. The license field intentionally uses a text input while preventing the stored real key from being returned in page HTML.

6. Configure administrator-role access for the addon if WHMCS requests it.

7. Open Addons > PDF Invoice.

8. Verify that the license status is active and review the default invoice, quote, branding, content, colour, viewer, protection, and language settings.

9. Select Save settings.

10. Select Install latest templates if activation did not already complete template installation.

11. Generate one test invoice PDF and one test quote PDF before enabling the module for production documents.

Upgrading PDF Invoice

1. Back up the WHMCS database and current active PDF templates.
2. Replace the files inside modules/addons/PDFInvoice with the new release files.
3. Keep the directory name unchanged.
4. Open the PDF Invoice addon page so WHMCS can run the module upgrade routine.
5. Confirm that the displayed version is 3.0.1.
6. Select Install latest templates to deploy any updated invoicepdf.tpl and quotepdf.tpl files. New backups are created before every replacement.
7. Generate invoice and quote test PDFs.

Recommended verification

Test at least the following cases before production deployment:

• Paid and unpaid invoices.
• Invoice and quote download/preview from WHMCS.
• Discounts, credits, zero-value rows, and long descriptions.
• Every currency used by the installation, especially currencies whose symbol requires Unicode support.
• Custom logo, signature, optional round company stamp, watermark, background, header, and footer artwork.
• One-page and multi-page documents.
• Payment links from generated invoice PDFs.
• LTR and RTL language output where applicable.
• Light and dark WHMCS administration themes.

Troubleshooting

The addon page is unavailable

• Confirm that a license key is present either on the addon page or in WHMCS Addon Modules configuration.
• Confirm that cURL and OpenSSL are enabled.
• Check the WHMCS activity log for the localized license error.
• Verify that the licensed domain, IP address, and native installation directory match the current installation.

Invoice or quote preview differs from the final PDF

• The addon-page preview is a lightweight visual prototype and does not request a real WHMCS billing record.
• Save settings and generate a test invoice or quote through WHMCS to verify final content, pagination, taxes, and conditional sections.
• Reinstall the latest templates from the addon page.

Logo, signature, or watermark does not appear

• Confirm that GD is enabled.
• Confirm that the WHMCS attachments directory is writable.
• Upload a valid PNG or JPEG within the displayed size restrictions.
• Save the corresponding enable setting after upload.

Settings appear unchanged

• Confirm that module specific tables exists and the WHMCS database user can insert and update rows.
• Check the WHMCS activity log for validation or database errors.
• Confirm that the addon page reports a successful save.
• Reinstall active templates if the changed feature also requires a newer template version.