Troubleshooting PDF Generation Errors and Special Characters

PDF Invoices

Use this when checkout or the Tools tab shows “ERROR Generating PDF,” tofu boxes instead of letters, or a PHP error inside Dompdf. Start with the latest zip from your account, then match the symptom in the table.

In this guide

1. Update first
2. Symptoms
3. Special characters and fonts
4. Common mistakes

Update first

1. Download the current zip from File downloads.
2. Confirm the version inside the zip matches the version shown on that page.
3. Replace the plugin on the site, then try a sample PDF from the Tools tab.

Symptoms

What you see	Likely cause	What to try
“ERROR Generating PDF. Please try again.”	The HTML template or a font failed while Dompdf rendered the file.	Download Sample PDF. Simplify the template. Check debug.log. See fonts below.
Blank squares (□) instead of letters	The PDF font does not include those glyphs.	Embed a font that covers the language. Japanese: Noto Sans JP guide linked below.
Call to undefined method Dompdf\Helpers::uniord()	Incomplete or mixed plugin files (old and new Dompdf together).	Delete the plugin folder and install a fresh zip from File downloads. Do not copy over the old folder.
Sample PDF works, old orders do not	Old stored files, or a template change not regenerated.	Generate Missing or Regenerate All on the Tools tab.

Special characters and fonts

Dompdf only draws characters that exist in the font used by the template. Arial or Times on the server often lack Slovak, Czech, Japanese, and similar glyphs.

• Japanese: follow How to set up Noto Sans JP.
• Other languages: embed a Unicode font that includes the needed characters, and set it on the body (and headings) in the template CSS.
• Keep the HTML charset as UTF-8.

Common mistakes

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