System font fails to load on Windows 7 - possible causes/fixes?

Itai itaisha at
Tue Nov 28 16:00:24 UTC 2017

Removing the font "Segoe UI Semilight" indeed solves the problem, although
there are still messages saying it failed to load "Segoe UI Regular".
However, this time the fallback is listed as Tahoma.

I have tested this on a system on which I am certain no custom fonts were
This font may have been pushed into Windows 7 in some Windows Update:

Or perhaps it got in the system via Office:

So I am not convinced it would be incompatible with Windows 7 - that would
be very strange, considering also only JavaFX seems to suffer from it.
Could it be that the error message simply means it had determined it needs
to use a fallback for displaying Hebrew glyphs? That may explain why the
error is still displayed after removing Segoe UI Semilight (this time only
for Segoe UI Regular). If the fallback mechanism only considers one step of
fallback then Segoe UI -> Segoe UI Semilight would fail, but removing
Semilight would make the fallback chain Segoe UI -> Tahoma, which would
Unfortunately I cannot test this by removing "Segoe UI Regular" as it is a
"protected system font", and so Windows won't allow me to delete it.

On Tue, Nov 28, 2017 at 5:35 PM, Itai <itaisha at> wrote:

> As far as I know this is a default Windows 7 installation, but it is
> entirely possible a font was added at some point. I don't know where it was
> sourced if that is the case.
> I will try removing this font to see if it makes a difference, but note
> that Prism also seems to be failing to load "Segoe UI Regular", which as I
> understand is meant to be the normal "Segoe UI" font?
> The only font this program loads by name is FontAwesome, which is embedded
> in the JAR. There is no reference to either Segoe UI or Segoe UI Semilight
> in the code, so if it tries to load them I'm assuming it is from the
> Windows fonts directory.
> On Tue, Nov 28, 2017 at 1:51 AM, Phil Race <philip.race at> wrote:
>> It seems to be mostly about this font  that is NOT your system font ..
>> but one
>> you are loading from somewhere.
>> Temp file created: C:\Users\user\AppData\Local\Te
>> mp\+JXF7252213042545373012.tmp^M
>> Mapping IDWriteFont="Segoe UI Semilight" Postscript
>> name="SegoeUI-Semilight" Win32 name="Segoe UI Semilight Regular"
>> The repeated error is for that one font
>> Mapping IDWriteFont="Segoe UI Semilight" Postscript
>> name="SegoeUI-Semilight" Win32 name="Segoe UI Semilight Regular"^M
>>         **** Failed to map IDWriteFont to Prism ****
>> So it looks as if DirectWrite does not like that font.
>> Where did you get it ?
>> according to Microsoft it is only available as part of Windows 8
>> So perhaps it isn't compatible with DW on Windows 7.
>> -phil
>> On 11/26/2017 12:16 AM, Itai wrote:
>>> I have recently come across a problem where some systems don't show
>>> Hebrew
>>> glyphs using JavaFX, where all other programs run perfectly fine.
>>> Changing the system font seems to be a workaround, but this is
>>> undesirable
>>> from the user's standpoint.
>>> At first I thought it was some issue with font substitution, so I ran the
>>> program with the option `-Dprism.debugfonts=true`, and apparently JavaFX
>>> completely fails to load the defined system fonts (which are the Windows
>>> 7
>>> standard, Segoe UI).
>>> I'm getting a lot of :
>>>       **** Failed to map IDWriteFont to Prism ****
>>> What can be the cause for this, and how do I go about further diagnosing
>>> the issue? I suppose this is some bug, but I'm not sure where or what
>>> exactly it is, so I don't know what details to give in a bug report.
>>> Attached is the full log of running with `-Dprism.debugfonts=true`.
>>> Thanks,
>>> Itai.

More information about the openjfx-dev mailing list