Invalid characters passed for attempted conversion, these have been ignored PHP 7.4 Dompdf #1512

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OVERLORD · 2026-02-05T01:06:16+03:00

OVERLORD commented

2026-02-05 01:06:16 +03:00

Originally created by @lucyhancock3533 on GitHub (Jan 30, 2020).

Describe the bug
When exporting a page to PDF using the default Dompdf renderer, on PHP7.4, and E_DEPRECIATION error is produced. This can be seen in the upstream at https://github.com/dompdf/dompdf/issues/2003. "Invalid characters passed for attempted conversion, these have been ignored".

Steps To Reproduce
Steps to reproduce the behavior:
Using a PHP 7.4 installation export any bookstack page to PDF with default dompdf renderer.

Expected behavior
A clear and concise description of what you expected to happen.

Your Configuration (please complete the following information):

Exact BookStack Version (Found in settings): BookStack v0.27.5
PHP Version: 7.4.2
Hosting Method (Nginx/Apache/Docker): Apache

Additional context
The issue may not be resolved upstream, the ticket is closed yet whether it is fixed or not is a bit unclear.

Originally created by @lucyhancock3533 on GitHub (Jan 30, 2020). **Describe the bug** When exporting a page to PDF using the default Dompdf renderer, on PHP7.4, and E_DEPRECIATION error is produced. This can be seen in the upstream at [https://github.com/dompdf/dompdf/issues/2003](https://github.com/dompdf/dompdf/issues/2003). "Invalid characters passed for attempted conversion, these have been ignored". **Steps To Reproduce** Steps to reproduce the behavior: Using a PHP 7.4 installation export any bookstack page to PDF with default dompdf renderer. **Expected behavior** A clear and concise description of what you expected to happen. **Your Configuration (please complete the following information):** - Exact BookStack Version (Found in settings): BookStack v0.27.5 - PHP Version: 7.4.2 - Hosting Method (Nginx/Apache/Docker): Apache **Additional context** The issue may not be resolved upstream, the ticket is closed yet whether it is fixed or not is a bit unclear.

OVERLORD added the 🐛 Bug 🏭 Back-End labels 2026-02-05 01:06:16 +03:00

OVERLORD closed this issue

2026-02-05 01:06:19 +03:00

OVERLORD commented

2026-02-05 01:06:21 +03:00

@ssddanbrown commented on GitHub (Mar 8, 2020):

Thanks for reporting this @lucyhancock3533.

I've just been testing on my dev system and it looks like this is no longer an issue for BookStack > v0.28 since that uses a later DomPDF version which includes the patch for PHP7.4.

Therefore I'll close this but if you do still see errors feel free to open a new issue.

@ssddanbrown commented on GitHub (Mar 8, 2020): Thanks for reporting this @lucyhancock3533. I've just been testing on my dev system and it looks like this is no longer an issue for BookStack > v0.28 since that uses a later DomPDF version which includes the patch for PHP7.4. Therefore I'll close this but if you do still see errors feel free to open a new issue.

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Reference: starred/BookStack#1512