Resolving TIA Portal V16 Update 3 Font Download Disabled Error in WinCC Professional Runtime

Engineers deploying WinCC Professional V16 Update 3 projects onto SIMATIC HMI panels frequently encounter a fault state where the Download font option under Runtime settings → Language & Font is grayed out (disabled). This article documents the root cause, affected software versions, complete resolution procedure, and platform-specific edge cases (Windows 10 vs. Windows 11) using only verified Siemens documentation and official TIA Portal behavior.

1. Problem Description

The reported fault presents as a non-editable checkbox in the TIA Portal project tree:

• Project → HMI device → Runtime settings → Language & Font → Download font checkbox is permanently grayed out.
• Clicking the disabled control triggers a Siemens error dialog that can only be acknowledged with OK.
• Project compilation finishes with errors referencing missing fonts (e.g., Roboto, Samsung Gulim, barcode symbology fonts).
• Font name appears correctly in Windows Control Panel → Fonts, but TIA Portal does not recognize it as an installable runtime font.
• Behavior reproduced on Windows 10 Enterprise (latest cumulative update) and Windows 11 Pro/Enterprise.

The reported project size at the time of the fault was approximately 30 HMI screens using a third-party typeface (Roboto) for multi-language display. The same symptoms have been independently confirmed on Comfort Panels that require barcode fonts to be loaded at runtime.

2. Affected Software and Hardware

3. Root Cause Analysis

The Download font checkbox is not a free-form toggle. TIA Portal enumerates the Windows font registry at design-time compile and only enables the option when at least one referenced font is registered in the per-machine (system) font store, not the per-user store. Drag-and-dropping a .ttf or .otf file into %WINDIR%\Fonts using File Explorer places the file in the directory but does not create the required HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts registry entry. TIA Portal reads the registry, not the folder, so the font is invisible to the compile pipeline and the download checkbox is locked.

Per Siemens TIA Portal Documentation — Languages and fonts in Runtime, the engineering system must recognize the font before any HMI device can be compiled, downloaded, or operated with that font. The documentation explicitly states: “Re-installation is required. After installing a font, restart the TIA Portal and completely re-compile your project. Only then can the HMI device be compiled.”

Two independent failure paths lead to the same symptom:

1. Drag-and-drop into the Fonts folder — copies the file but does not register it. Visible in Control Panel → Fonts, invisible to TIA Portal.
2. In-place Windows 10 → Windows 11 upgrade — the upgrade can prune non-Microsoft user-installed fonts from %LOCALAPPDATA%\Microsoft\Windows\Fonts and may also strip per-user registry entries. The font may be re-listed in Control Panel but absent from the per-machine store that TIA Portal reads.

4. Step-by-Step Resolution

4.1 Prerequisites

• Local Administrator account on the engineering station.
• TIA Portal V16 Update 3 (or later) installed and licensed.
• The original .ttf or .otf font file. If only Google Fonts archive is available, extract the static Roboto-Regular.ttf, Roboto-Bold.ttf, etc. Do not use variable-font .ttf files for HMI runtime; they are not always supported by older panel firmware.
• All TIA Portal instances closed before installing the font.

4.2 Correct Installation Procedure (Windows 10 / Windows 11)

1. Close every instance of TIA Portal and any TIA Portal helper processes (S7PCT, HMIRTP, Siemens.Automation.ObjectStore.FileServer.exe). Use Task Manager → Details to confirm.
2. Open File Explorer and navigate to the folder containing the font file.
3. Right-click the .ttf file (or multi-select all required faces such as Roboto-Regular.ttf, Roboto-Bold.ttf, Roboto-Italic.ttf).
4. Choose Install for all users — not the plain Install option.
5. If UAC prompts, provide Administrator credentials.
6. Verify the registration by opening Control Panel → Fonts and confirming the font is shown without a small user-account overlay icon (the overlay indicates per-user install only).
7. Open Registry Editor (regedit) and navigate to HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts. The font should now appear with its full filename (e.g., Roboto Regular (TrueType) = Roboto-Regular.ttf).

4.3 TIA Portal Recovery Sequence

1. Reboot the engineering station. A reboot is required to flush font subsystem caches and to ensure the TIA Portal background services pick up the new HKLM entry.
2. Start TIA Portal V16 Update 3 as Administrator (right-click → Run as administrator).
3. Open the affected project.
4. Right-click the HMI device in the project tree and choose Compile → Software (rebuild all). A full rebuild — not an incremental compile — is required to force re-evaluation of the font table.
5. Navigate to Runtime settings → Language & Font. The Download font checkbox is now editable.
6. Enable the checkbox, save the project, and perform a second rebuild before downloading to the panel.

4.4 Verification

5. Windows 11 Post-Upgrade Edge Case

Engineers who perform an in-place upgrade from Windows 10 to Windows 11 may find that previously-working third-party fonts (e.g., Samsung Gulim, GulimChe, custom Korean typefaces) are silently removed. The fonts may still appear in the listing inside TIA Portal's Language & Font dialog — because TIA Portal caches a project-local reference — but the Download font checkbox remains disabled.

Recovery sequence specific to Windows 11:

1. Open Settings → Personalization → Fonts. Confirm whether the font is listed under Installed fonts or only under Available fonts.
2. If listed as Available, the font is present on disk but not registered. Click the font and select Install (this is the modern Windows 11 Install for all users equivalent and writes to the HKLM store).
3. If the font is missing entirely, re-download it from the manufacturer (e.g., Samsung Gulim is part of the Microsoft Korean language pack). For non-Microsoft fonts, re-acquire the original .ttf.
4. Delete the cached project font reference: in TIA Portal, open Project tree → Languages & Resources → Project languages, remove the font entry, save, then re-add it.
5. Reboot, then re-launch TIA Portal as Administrator and perform the full rebuild sequence from Section 4.3.

6. Comfort Panel Barcode Font Symptom

An independent but related symptom affects Comfort Panels (TP/KP series) when barcode fonts (Code 39, Code 128, DataMatrix, QR) are referenced in the project. The error message observed is:

Unable to Download Barcode Fonts to Comfort Panel.

The barcode font must be installed on the engineering station using the procedure in Section 4.2, and the panel firmware must be capable of rendering the symbology. Verify the panel firmware version against the Siemens Industry Online Support compatibility list. The Comfort Panel firmware must be at least the version that ships with the corresponding TIA Portal version (e.g., V16 Update 3 panels ship with firmware compatible with TIA V16 Update 3). If a mismatched firmware is in service, upgrade the panel firmware through ProSave or TIA Portal's Online → HMI Device Maintenance menu before retrying the font download.

7. Diagnostic Command Reference

Use these commands from an elevated PowerShell window to verify font registration programmatically before re-running TIA Portal:

# List all fonts registered per-machine (HKLM) 
Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts' | 
  Select-Object -Property PSChildName |
  Format-Table -AutoSize

# Confirm a specific font entry exists
$key = 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts'
Get-ItemProperty -Path $key | 
  Get-Member -MemberType NoteProperty |
  Where-Object { $_.Name -like '*Roboto*' } |
  Select-Object Name

# Force font cache rebuild after manual install
$fontCache = "$env:WINDIR\System32\FNTCACHE.DAT"
if (Test-Path $fontCache) { Remove-Item $fontCache -Force }
# Reboot is required for the new cache to take effect.

If Get-ItemProperty returns no row matching the font name, the install is incomplete and TIA Portal will refuse to enable the download checkbox.

8. Troubleshooting Matrix

9. Best Practices for Multi-Language HMI Projects

• Centralize font files in a version-controlled engineering share (\\corp\hmi\fonts\) to prevent per-engineer divergence.
• Document the install path in the project functional specification so that any engineer who inherits the workstation can replicate the environment in under 10 minutes.
• Test on a clean Windows 10/11 VM before promoting the project to production to catch missing-font regressions.
• Avoid variable fonts (.ttf with multiple axes). Comfort Panel firmware predating V16 may not parse them; pin to static instances.
• Use the TIA Portal Openness API in build pipelines to assert that HmiRuntimeSettings.Fonts contains the expected font list before automated deployment.
• Enable Download font explicitly in every screen that uses a non-default face. Without this option, the panel substitutes the closest available face at compile time and the project will not reflect the intended typography.
• Re-compile fully after any change to Language & Font; incremental compile does not refresh font metadata.

10. Frequently Asked Questions