WordPress/gutenberg

Custom font upload not working

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#72,265 opened on Oct 11, 2025

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 (15 comments) (0 reactions) (1 assignee)JavaScript (3,893 forks)batch import
Good First Issue[Feature] Font Library[Status] In Progress[Type] Bug

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Description

Description

When trying to install this font it wouldn't complete and instead we are seeing a browser console error.

Step-by-step reproduction instructions

  1. Go to Appearance > Editor
  2. Styles > Fonts
  3. Try uploading this font:

AaDaoShuRi-LangManHeiTi-2.ttf.zip

Screenshots, screen recording, code snippet

The console renders:

Uncaught (in promise) SyntaxError: Invalid font data in ArrayBuffer

Th workaround is to convert it to a .woff2. I've used https://transfonter.org/

Environment info

WordPress 6.9 and the current stable version

Please confirm that you have searched existing issues in the repo.

  • Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

  • Yes

Please confirm which theme type you used for testing.

  • Block
  • Classic
  • Hybrid (e.g. classic with theme.json)
  • Not sure

Contributor guide

Research direction
Examine the font upload handler in the Gutenberg source code. Look for where ArrayBuffer is converted to a font face and identify why .ttf files cause 'Invalid font data'. Check the blob to font conversion logic and add support for TTF formats or improve error handling.
Tech stack
javascriptreact
Domain
frontend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptReact
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70