Fix Font Tofu for CJK Languages on Teto OS

Disclaimer This method was tested on Windows 10 IoT Enterprise LTSC 2021, Build 22H2 (19045). It may not work on other versions, so double-check online or ask an AI assistant if you run into issues.

"Tofu" refers to the empty boxes (□) that appear when a font has no glyph for a character. This usually happens with East Asian languages (Japanese, Korean, Chinese) when the matching fonts and language packs are not installed. This guide walks through installing them.

Bypass WSUS/Group Policy

On Teto OS, or when Windows is not activated, WSUS/Group Policy can block the download of language packs. To work around this, temporarily point Windows Update at the public update servers instead of the WSUS server.

Run the following commands to temporarily disable the WSUS/Group Policy restriction:

powershell

# Temporarily allow a direct Windows Update connection
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate" -Name "DisableWindowsUpdateAccess" -Value 0
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer" -Value 0

# Restart the Windows Update service
Restart-Service wuauserv -Force

Once the language packs are installed, restore the original setting with the following commands:

powershell

Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate\AU" -Name "UseWUServer" -Value 1
Restart-Service wuauserv -Force

Install the language packs

Each language pack is installed with DISM using its language code. If you need a language that isn't listed below, search online or ask an AI assistant for the correct capability name.

Japanese (JP)

powershell

# Font
DISM /Online /Add-Capability /CapabilityName:Language.Fonts.Jpan~~~und-JPAN~0.0.1.0
# Basic language support
DISM /Online /Add-Capability /CapabilityName:Language.Basic~~~ja-JP~0.0.1.0

Korean (KR)

powershell

# Font
DISM /Online /Add-Capability /CapabilityName:Language.Fonts.Kore~~~und-KORE~0.0.1.0
# Basic language support
DISM /Online /Add-Capability /CapabilityName:Language.Basic~~~ko-KR~0.0.1.0

Chinese (CN)

powershell

# Font (Simplified)
DISM /Online /Add-Capability /CapabilityName:Language.Fonts.Hans~~~und-HANS~0.0.1.0
# Font (Traditional)
DISM /Online /Add-Capability /CapabilityName:Language.Fonts.Hant~~~und-HANT~0.0.1.0
# Basic language support (Simplified)
DISM /Online /Add-Capability /CapabilityName:Language.Basic~~~zh-CN~0.0.1.0
# Basic language support (Traditional)
DISM /Online /Add-Capability /CapabilityName:Language.Basic~~~zh-TW~0.0.1.0

After the packs are installed, restart your computer to apply the changes.