Fontconfig error: Cannot load default config file: No such file: (null))

[lorenzoappetito-archimediasistemi]

Code:

private static async Task AddTextToVideo(string inputVideoPath, string outputVideoPath, string text, 
                                         Guid accountId, int textFrequency, int textDuration)
{
    FFMpegArguments.FromFileInput(inputVideoPath)
        .OutputToFile(outputVideoPath, true, options => options
            .WithVideoFilters(filterOptions => filterOptions
                .DrawText(drawTextOptions[0])
            )
        )
        .NotifyOnProgress(ProgressHandler)
        .ProcessSynchronously();
}

private static DrawTextOptions[] CreaCroce(string text, int textFrequency, int textDuration, int width, int height)
{
    var drawTextOptionsArray = new DrawTextOptions[5];

    drawTextOptionsArray[0] = DrawTextOptions.Create(text, FontName)
        .WithParameter("fontfile", @"C:\home\site\wwwroot\arial.ttf")
        .WithParameter("fontsize", FontSize.ToString(CultureInfo.InvariantCulture))
        .WithParameter("fontcolor", "white")
        .WithParameter("box", "1")
        .WithParameter("boxcolor", "black@0.5")
        .WithParameter("boxborderw", "5")
        .WithParameter("x", @"if(eq(mod(n\\,200)\\,0)\\,rand(0\\,(w-text_w))\\,x)")
        .WithParameter("y", @"if(eq(mod(n\\,200)\\,0)\\,rand(0\\,(h-text_h))\\,y)")
        .WithParameter("enable", $@"lt(mod(t\\,{textFrequency})\\,{textDuration})");
}

Error:

ffmpeg exited with non-zero exit-code (-1073741819 - ffmpeg version 6.1-full_build-www.gyan.dev Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 12.2.0 (Rev10, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --pkg-config=pkgconf --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-dxva2 --enable-d3d11va --enable-libvpl --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      58. 29.100 / 58. 29.100
  libavcodec     60. 31.102 / 60. 31.102
  libavformat    60. 16.100 / 60. 16.100
  libavdevice    60.  3.100 / 60.  3.100
  libavfilter     9. 12.100 /  9. 12.100
  libswscale      7.  5.100 /  7.  5.100
  libswresample   4. 12.100 /  4. 12.100
  libpostproc    57.  3.100 / 57.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\home\site\wwwroot\input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.19.102
  Duration: 00:00:05.53, start: 0.000000, bitrate: 2141 kb/s
  Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 2022 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 127 kb/s (default)
    Metadata:
      handler_name    : ISO Media file produced by Google Inc.
      vendor_id       : [0][0][0][0]
Fontconfig error: Cannot load default config file: No such file: (null))

The TTF file exists but there is no way to make this code work. Some idea?

Everything works locally, but not on an Azure Function.

I tried this command from the console on Azure and it works.

ffmpeg.exe -i input.mp4 -vf "drawtext=fontfile=arial.ttf:fontsize=24:fontcolor=green:text=HelloWorld" output.mp4

Thank you