Fix TIA Portal Tahoma Font Not Installed Error on KTP 700 Basic

Problem Description

When compiling a Siemens HMI project targeting a KTP 700 Basic DP (or the PN variant) in TIA Portal V13 SP1 Update 9, the HMI compile step halts and emits the error:

The Tahoma Font is not Installed

The message is displayed in the TIA Portal Info / Compile and check window during the Compile HMI step. The HMI image cannot be downloaded to the panel until the condition is cleared, because the WinCC HMI compile step requires Tahoma to be present on the engineering station so it can resolve the default font table for the runtime image.

Engineers frequently report that Tahoma appears to be installed - the file is visible in C:\Windows\Fonts, the font works in Microsoft Word, and the Windows Fonts control panel shows a valid glyph preview. The compile error still appears because the TIA Portal host check is not a simple file-system check: it validates the Win32 font enumeration namespace and the system font collection exposed through System.Windows.Media.Fonts.SystemFontFamilies. A corrupted registry entry, a stale font cache, a missing system-wide install, or a non-elevated compile process can all pass the file-system check while failing the WinCC compile check.

Common symptoms that accompany the error:

• Compile output shows The Tahoma Font is not Installed followed by Compile error (0001): Aborted.
• HMI download fails immediately with Download to device failed: HMI image not generated.
• Re-opening the project and recompiling reproduces the error every time, even after a clean reboot.
• The error appears only on the HMI compile step, not on the PLC compile step. The PLC project compiles and downloads normally.

Affected Products and Software Versions

The Tahoma error has been observed on the following product generations. Confirm your engineering station matches one of these versions before applying a fix.

The error is most often reported on V13 SP1 Update 9 and on V14 / V14 SP1 projects that were originally created in V13 and re-saved in the newer version. The default TIA Portal project language English (United States) maps to Tahoma in WinCC; the language Deutsch (Deutschland) also maps to Tahoma, while other locales map to different default fonts. The mapping is exposed in Project tree > Languages and Fonts.

The KTP 700 Basic panel itself does not need Tahoma as a font on the panel; Tahoma is required only on the engineering station to compile the runtime image. The runtime image embeds the glyph tables for the languages enabled in the project, so the panel renders Tahoma text correctly even if the engineering station has Tahoma removed after the project is compiled.

KTP 700 Basic part numbers (typical, region-specific variants exist):

• KTP 700 Basic DP: 6AV2 127-1GA00-0AX0
• KTP 700 Basic PN: 6AV2 127-1KA00-0AX0

Root Cause Analysis

The WinCC HMI compile step enumerates fonts through the System.Drawing.Text.InstalledFontCollection and System.Windows.Media.Fonts.SystemFontFamilies APIs. The Tahoma error is raised when the enumeration returns an empty result for the Tahoma family name. Five primary root causes have been observed in the field:

1. Font file absent or moved. tahoma.ttf and tahomabd.ttf are missing from %WINDIR%\Fonts. This is the most common cause on stripped-down engineering stations, on VDI images that have not been sysprepped with the base font set, and on Windows 10 1809+ systems where Tahoma has been moved to an optional feature.
2. Registry entry present, file absent. The registry key HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts references the Tahoma file name, but the actual .ttf is not in C:\Windows\Fonts. The Windows Font Control Panel hides Tahoma because the file cannot be loaded, but file-system checks appear to pass.
3. Stale font cache. The Windows font cache service holds a corrupted version of Tahoma in %WINDIR%\System32\FNTCACHE.DAT. The file on disk is good, but enumeration returns an error because the cache has not been refreshed.
4. Insufficient privilege. TIA Portal launched without Administrator rights cannot read the per-user font enumeration namespace. Tahoma is visible to Word and Notepad, but the WinCC compile runs in a separate process with a restricted token that cannot enumerate the system-wide font store.
5. Project language / runtime locale mismatch. The HMI project is set to English (United States) in the HMI runtime settings, but the project node itself uses a different default language in Project tree > Languages and Fonts > Project language. The compile step uses the project language to resolve Tahoma; if the project language is not bound to Tahoma, the compile step reports Tahoma missing even when it is installed.

A secondary cause observed in VDI environments: the engineering station is a non-persistent VDI image, and Tahoma is installed in the per-user profile rather than the system-wide font store. After re-login, the font disappears. The fix is to install Tahoma into the master image, not the user profile.

On Windows 10 1809 and later, the Settings > Apps > Optional features panel includes Microsoft Tahoma Font Family as an optional add-on. If it has been removed or was never installed through the optional features path, the file is absent from C:\Windows\Fonts even on a fully patched Windows 10 image. This is a documented Windows behavior, not a TIA Portal defect.

Pre-Diagnosis Checklist

Before applying any fix, capture the following baseline so the engineer can verify the regression later and so an escalation to Siemens Support has the data they need.

1. Open Start > Control Panel > Fonts (Windows 7) or Settings > Personalization > Fonts (Windows 10) and confirm Tahoma is listed with a valid glyph preview.
2. Open cmd.exe as Administrator and run dir "%WINDIR%\Fonts\tahoma*.ttf". The expected output is two files: tahoma.ttf and tahomabd.ttf.
3. Open regedit.exe and navigate to HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts. Confirm the values Tahoma (TrueType) = tahoma.ttf and Tahoma Bold (TrueType) = tahomabd.ttf exist as REG_SZ entries.
4. Open Help > About TIA Portal in the TIA Portal menu and record the exact version string, e.g. V13 SP1 Update 9 or V14 SP1 Update 6.
5. Open the TIA Portal project, expand the HMI node, and check Project tree > Languages and Fonts > Project language and Project tree > Languages and Fonts > Reference language. Both should be English (United States) for Tahoma to be the default font.
6. Open Control Panel > Region and Language > Administrative > Change system locale and confirm the current system locale. The system locale does not have to match the project language, but if it is set to a non-Tahoma locale, the WinCC compile may pick a different default font.
7. Open Control Panel > Programs and Features and confirm WinCC is installed. The exact entry is SIMATIC WinCC Vxx SPx. If only STEP 7 Vxx is installed, the WinCC HMI compile step is missing and Tahoma is never resolved.
8. Run eventvwr.msc, open Windows Logs > Application, and filter for Source: .NET Runtime and Source: SideBySide events during the last compile. SideBySide errors that mention Microsoft.VC90.CRT or msvcr90.dll have been observed to cause WinCC to abort the font enumeration before Tahoma is read.

Save the output of each step. A clean baseline makes it possible to tell which fix actually resolved the error.

Solution 1: Install or Repair Tahoma with Admin Rights

This is the first remedy to attempt and the only one that fixes the issue in approximately 60 percent of field reports. It addresses root cause 1 (file absent) and root cause 4 (insufficient privilege).

1. Close TIA Portal and any application that may be holding a handle on the Tahoma file (Microsoft Office, browser, AutoCAD).
2. Open cmd.exe as Administrator. Confirm by typing whoami /groups | find "S-1-16-12288". The High Mandatory Level SID indicates the elevated token.
3. Copy tahoma.ttf and tahomabd.ttf to a temporary folder, e.g. C:\Temp\Tahoma\. The source may be a clean Windows 7 SP1 install, the engineering station backup, or the Windows installation media.
4. Right-click each .ttf and select Install (or Install for all users if offered). The file is copied to %WINDIR%\Fonts and a registry entry is created in HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts.
5. Alternatively, install from the command line:

   copy /y C:\Temp\Tahoma\tahoma.ttf   "%WINDIR%\Fonts\"
   copy /y C:\Temp\Tahoma\tahomabd.ttf "%WINDIR%\Fonts\"
   reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts" /v "Tahoma (TrueType)"        /t REG_SZ /d tahoma.ttf   /f
   reg add "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts" /v "Tahoma Bold (TrueType)"   /t REG_SZ /d tahomabd.ttf /f

6. Open Control Panel > Fonts and confirm Tahoma and Tahoma Bold are now listed with a real glyph preview, not a generic placeholder.
7. Confirm enumeration through the WPF API:

   powershell -NoProfile -Command "Add-Type -AssemblyName PresentationCore; [System.Windows.Media.Fonts]::SystemFontFamilies | Where-Object { $_.Source -match 'Tahoma' } | ForEach-Object { $_.Source }"

   The expected output contains two entries: Tahoma and Tahoma Bold.
8. Reboot the engineering station. The font cache is rebuilt at boot.
9. Launch TIA Portal as Administrator, open the HMI project, and re-run Compile > Software (rebuild all).

Solution 2: Remove Stale Tahoma Variants and Rebuild the Font Cache

Use this remedy if Tahoma is listed in the Fonts control panel but the file preview is broken (red X, generic box, or zero-byte preview). A broken preview means the file is registered but cannot be loaded by the Windows font subsystem. It addresses root cause 2 (registry/file mismatch) and root cause 3 (stale font cache).

1. Close TIA Portal and all Office applications.
2. Open Control Panel > Fonts. Locate Tahoma and Tahoma Bold. Right-click > Delete. Confirm the deletion.
3. Open regedit.exe as Administrator. Navigate to HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts and delete the values:
   • Tahoma (TrueType)
   • Tahoma Bold (TrueType)
   • any Tahoma * variant that remains
4. Navigate to HKCU\Software\Microsoft\Windows NT\CurrentVersion\Fonts and remove any user-scope Tahoma entries. Stale per-user entries can shadow system entries.
5. Stop the Windows Font Cache service:

   net stop FontCache
   net stop FontCache3.0.0.0

   On Windows 7 the second service may not exist; that is normal.
6. Delete the font cache files:

   del /q /a "%WINDIR%\System32\FNTCACHE.DAT"
   del /q /a "%WINDIR%\System32\FontCache-System.dat"
   del /q /a "%WINDIR%\System32\FontCache-User.dat"
   del /q /a "%WINDIR%\ServiceProfiles\LocalService\AppData\Local\FontCache\FontCache-System.dat"
   del /q /a "%WINDIR%\ServiceProfiles\LocalService\AppData\Local\FontCache\FontCache-User.dat"

7. Start the Font Cache service:

   net start FontCache
   net start FontCache3.0.0.0

8. Reboot the engineering station. Windows rebuilds the font cache from C:\Windows\Fonts and the registry.
9. Reinstall Tahoma using Solution 1, steps 3 through 7.
10. Re-run the PowerShell enumeration test from Solution 1, step 7.

If Tahoma still does not enumerate after the cache rebuild, open Event Viewer > Applications and Services Logs > Microsoft > Windows > Windows Error Reporting and look for any Application Error events from explorer.exe or dwm.exe that mention tahoma.ttf. These confirm the font file is corrupt and must be replaced from a clean source.

Solution 3: Align Project Language and Runtime Locale

Use this remedy if Tahoma is correctly installed on the engineering station and the Win32 enumeration test passes, but the compile error persists. The cause is a mismatch between the project language and the default font mapping in WinCC (root cause 5).

1. Open the TIA Portal project.
2. Select the HMI device in the project tree, e.g. HMI_1 [KTP 700 Basic DP].
3. Open Properties > Languages and Fonts in the inspector window.
4. Confirm the Project language field is set to English (United States). If it is set to a different language, click the dropdown, select English (United States), and click Apply.
5. Confirm the Reference language field is also English (United States). The reference language is the language used for the runtime default font lookup.
6. Open Project tree > Languages and Fonts > Runtime languages. Confirm English (United States) - Tahoma is enabled. Disable any other language that uses a font other than Tahoma for the test compile (e.g. Arabic (Saudi Arabia) - Arial).
7. Save the project. The save action writes the language and font mapping into the HMI project metadata.
8. Re-run Compile > Software (rebuild all).

If the error still persists, set the project language to German (Germany) temporarily, recompile, and then switch back to English (United States). This forces WinCC to re-build the language table and is a documented workaround in the Siemens Knowledge Base for V13 SP1 projects opened in V14.

Solution 4: Run TIA Portal as Administrator

Use this remedy in addition to Solutions 1 through 3. The WinCC HMI compile step runs in a separate process and may fail to enumerate Tahoma if TIA Portal is not elevated.

1. Close TIA Portal.
2. Right-click the TIA Portal shortcut and select Run as administrator. Confirm the UAC prompt.
3. Alternatively, right-click the TIA Portal executable (default location C:\Program Files\Siemens\Automation\Portal V13\Bin\Siemens.Automation.Portal.exe) and pin it to the Start menu with Run this program as an administrator enabled in Properties > Compatibility > Settings.
4. For domain-joined engineering stations, open Local Security Policy > Local Policies > Security Options > User Account Control: Run all administrators in Admin Approval Mode and confirm it is Enabled. Disabling Admin Approval Mode bypasses the elevation prompt and is not recommended.
5. Open the project and re-run the compile.

If the engineering station is a Citrix or VDI session, the elevation must be granted by the Citrix policy. Citrix Group Policy > Computer Settings > Administrative Templates > Citrix Components > Citrix Workspace > User authentication must allow the elevated token. A non-elevated VDI session will not be able to read the system-wide font enumeration.

Solution 5: Repair or Upgrade the TIA Portal Installation

If the engineering station has been upgraded through multiple TIA Portal versions, the WinCC component may have been left in a partial state. A repair re-installs all WinCC binaries without touching the user projects. If repair is not sufficient, upgrade to a supported TIA Portal version.

1. Close TIA Portal and the TIA Portal Help system.
2. Open Control Panel > Programs and Features (Windows 7) or Settings > Apps & Features (Windows 10).
3. Locate the entry SIMATIC TIA Portal Vxx. Right-click and select Repair.
4. Follow the prompts. The repair process re-installs the WinCC component, the TIA Portal framework, and the HMI runtime. It can take 15 to 45 minutes depending on the installation size.
5. Reboot the engineering station when prompted.
6. Launch TIA Portal as Administrator, open the project, and re-run the compile.
7. If Repair is greyed out, the installation is managed by an MSI transform. Run the original installation media and select Modify, then re-check the WinCC option. The default TIA Portal installation includes WinCC; if it has been deselected, the HMI compile step is incomplete and Tahoma is not resolved.
8. If repair does not resolve the issue, upgrade the project. In the source TIA Portal version run Project > Archive. Install the target TIA Portal version (e.g. V17 with the latest update) on a separate engineering station. Open TIA Portal V17 and select Project > Retrieve > Open archive. The migration step re-resolves the HMI device to the matching firmware image and rebuilds the HMI compile context.

For V13 SP1 specifically, the WinCC component is SIMATIC WinCC V13 SP1 and the runtime component is WinCC Runtime Advanced V13 SP1. KTP 700 Basic panels use WinCC Runtime Advanced, not Professional. Do not install WinCC Runtime Professional unless the project also includes a WinCC Professional panel.

Verification Procedure and Diagnostic Commands

After applying any of the five solutions, the engineer must verify that the Tahoma error no longer appears and that the HMI image can be downloaded to the panel. The following commands confirm Tahoma is correctly installed and the WinCC HMI compile is reading the right font table. All commands must be run from an elevated cmd.exe.

1. Open TIA Portal as Administrator.
2. Open the HMI project.
3. Select Compile > Software (rebuild all). The compile output window should complete with status No errors, no warnings or only the expected warnings (e.g. Connection to PLC not established).
4. Confirm the Info window no longer contains the line The Tahoma Font is not Installed. If the error is still present, capture the full compile log: right-click the Info window > Save log to file. The log contains the file path of the font lookup and the Win32 error code, which Siemens Support requires for escalation.
5. Right-click the HMI device in the project tree and select Download to device > Software and firmware. Confirm the device is online (ping or accessible on the configured PROFINET / PROFIBUS subnet).
6. Wait for the download to complete. The progress bar should reach 100% and the panel should reboot automatically.
7. On the panel, open the start screen and check that all text strings render in the default Tahoma font. The text should not be substituted with a generic sans-serif.
8. Open the TIA Portal diagnostic view (Online > Online & Diagnostics) and confirm the panel reports No diagnostic errors.

For WinCC HMI compile logging, enable verbose logging in TIA Portal: Options > Settings > General > Trace. Set the trace level to Verbose for the modules HMICOMP, HMICORE, and WINCC. The trace log is written to %LOCALAPPDATA%\Siemens\Automation\Portal Vxx\Logs\ and contains the exact file path and Win32 error code of the Tahoma lookup. This log is required for Siemens Support to reproduce the issue.

For long-term verification, schedule a weekly compile of the project on a build server. The TIA Portal Teamcenter Gateway and the SIMATIC Automation Tool (SAT) support batched compile and CI integration. A scheduled compile catches any regression of the Tahoma issue (for example, after a Windows update replaces Tahoma with a different version).

Escalation Path and Related Errors

If Solutions 1 through 5 do not resolve the Tahoma error, escalate to Siemens Industry Online Support. Prepare the following information before opening a Support Request:

• TIA Portal version, build number, and installed updates (from Help > About TIA Portal)
• Operating system version and patch level (from winver)
• Exact error message text and the compile log file (right-click Info window > Save log to file)
• Output of the diagnostic commands in the previous section
• KTP 700 Basic part number and image version
• Output of wmic product where "name like '%%WinCC%%'" get name,version
• Output of the TIA Portal trace log in %LOCALAPPDATA%\Siemens\Automation\Portal Vxx\Logs\
• Steps already attempted (Solutions 1 through 5) with their results

Submit the Support Request through the Siemens Industry Online Support portal. Reference the KTP 700 Basic part number and the WinCC version in the title. Siemens typically responds within 1 to 3 business days for paid support contracts and 3 to 5 business days for free registration. The response will include a Knowledge Base article link, a hotfix (HSP) link, or a request for a remote session through the Premium Support channel.

The Tahoma error is one of several font-related errors that WinCC can emit during an HMI compile. The following table maps the most common errors to their root causes and remedies.

Errors that are not font-related but commonly reported in the same project:

• HMI Tag connection: No connection to PLC - PROFINET / PROFIBUS configuration mismatch. Check Devices & Networks > Network view > Connections.
• HMI device is not online - Subnet configuration mismatch between PLC and HMI. Check IP / PROFIBUS address.
• License is missing: WinCC RT Advanced - License key not installed. Use the Automation License Manager to install the license.
• Image version mismatch: panel expects Vxx.x.x.x - The TIA Portal project image version does not match the panel image. Update the panel through ProSave.

For further information on Tahoma, the Microsoft Typography Tahoma family page documents the original font design, glyph coverage, and the variants Tahoma and Tahoma Bold. The page is the canonical reference for Tahoma as a system font on Windows 7, Windows 10, and Windows 11.