Kindle Oasis rejects bionic-reading .ttf as “invalid” and keeps triggering Windows drive errors #47
Description
Hi
— I’m posting because I’m actively trying to fix this, not abandon it.
I’m using a Kindle Oasis and attempting to install a bionic-reading style font (bolded leading syllables) via USB. The font is a .ttf, opens and previews perfectly on Windows, and has been reduced to Regular + Bold only (no italics, no variable font).
What I’ve already done:
• Files placed directly in /fonts/ (no subfolders)
• Multiple safe ejects + hard reboots
• Windows scan/repair (sometimes reports clean, warning still returns)
What’s happening:
• Windows repeatedly flags the Kindle with “There’s a problem with this drive”
• When interacting with the font on the Kindle drive, I get
“The requested file is not a valid font file” (see attached image)
• This appears font-specific, not random
Important clarification:
I know Kindle doesn’t “officially” support bionic reading — but this is a static font, not an app or runtime feature. I’m trying to understand what exactly Kindle rejects at the font table / metadata level, because Windows clearly accepts it.
What I’m looking for help with:
• Are there specific OpenType tables Kindle Oasis firmware rejects?
• Has anyone successfully recompiled or stripped bionic-reading fonts to work on Kindle?
• Is this a known issue with Kindle’s font parser vs Windows’ tolerance?
I’m not looking for “don’t do it” or “just use another font” — I’m trying to identify what needs to be changed in the font itself so it’s accepted.
If anyone has experience rebuilding fonts for Kindle compatibility, I’d really appreciate the insight.