Intermittent Font Enumeration Issues on Windows

[fahrio]

Hi,

I'm experiencing intermittent issues with the Local Font Access API on Windows. My web application (https://wordmark.it) relies on the API to enumerate installed system fonts. Every now and then, users report a significant drop in the number of fonts visible in the app. For instance, a user with over 3,000 installed fonts, who has been using the app for years, would report that they can now only see around 400 fonts in the enumeration results.

This issue occurs without any changes on my side and therefore seems related to changes on the user's end. Users confirm that they can see the missing fonts in other native applications.

Key Details:

• Issue: Inconsistent results from queryLocalFonts() with significantly fewer fonts enumerated than expected.
• Platform: Windows 10/11
• Browsers: Affected in Chromium-based browsers (Chrome, Edge).
• Reproduction: The issue is inconsistent and seems to occur after Windows updates.
• Expected Behavior: The API should reliably enumerate all fonts installed on the users' operating system.

Investigation So Far:

• I don't know how to replicate the issue on my development environment.
• I’m aware of past issues where the API could only access fonts in the Windows\Fonts folder. However, this limitation was reportedly resolved several years ago (see related Chromium bug report).
• The issue might be related to changes in Windows permissions, updates affecting font directories, or technical details in how browsers access system fonts.

Request:

I’ve been trying to resolve this issue by instructing users to test different solutions for quite some time, but nothing has worked so far, and many users give up and abandoned the app. I'm reaching out here as a last resort.

• Could anyone clarify how, and if, Windows font directory structures and user-scoped font installations impact font detection with the API? Are there any known limitations related to these aspects that might cause such inconsistencies?
• Are there recommended debugging steps I can follow to diagnose the issue on Windows environments?
• If this is a potential bug, I’m happy to provide additional information or try connecting with users willing to assist in testing.

Thank you for your time and effort in maintaining this API!