stride3d/stride · error · InvalidOperationException

The specified DefaultCharacter is not part of this font.

Error message

The specified DefaultCharacter is not part of this font.

What it means

Stride's OfflineRasterizedSpriteFontCompiler rasterizes glyphs and requires a fallback glyph for characters missing from the font. After building the glyph list it checks that the asset's DefaultCharacter was actually rasterized; if not, it throws this InvalidOperationException. A default character that is not in the font would produce a null fallback glyph at render time, so the compiler fails fast during asset build.

Solutions

1. Open the font asset and set DefaultCharacter to a character verified to exist in the font file ('?' or '*' are almost always present).
2. If the font lacks a suitable default, switch to a font file with broader coverage (a full Unicode font).
3. Alternatively set DefaultCharacter to null/0 so no default-glyph validation applies, if the pipeline allows it.
4. Verify actual coverage with a font inspection tool (fontforge, OS character map) before setting the value.

Example fix

// before (font asset)
<DefaultCharacter>é</DefaultCharacter>
// after
<DefaultCharacter>?</DefaultCharacter>

// before compiling, confirm the default char exists in the font's cmap
if (asset.DefaultCharacter != default && !FontCoversCharacter(fontPath, asset.DefaultCharacter.Value))
    asset.DefaultCharacter = '?'; // safe fallback present in nearly all fonts

bool IsValidDefaultCharacter(SpriteFontAsset asset) =>
    asset.DefaultCharacter == default ||
    FontCoversCharacter(asset.FontSource.GetFontPath(), asset.DefaultCharacter.Value);

try
{
    var glyphs = OfflineRasterizedFontCompiler.Compile(factory, asset);
}
catch (InvalidOperationException ex) when (ex.Message.Contains("DefaultCharacter"))
{
    asset.DefaultCharacter = '?';
    glyphs = OfflineRasterizedFontCompiler.Compile(factory, asset); // retry with safe default
}

When it happens

Trigger: Calling ImportFont in OfflineRasterizedFontCompiler (directly or via Compile, which feeds GetCharactersToImport/ImportFont) with a SpriteFontAsset whose DefaultCharacter is a codepoint the font file does not contain — e.g. DefaultCharacter='é' on an ASCII-only TTF, or a character outside the compiled CharacterSet.

Common situations: Setting DefaultCharacter in a font asset to a symbol the TTF lacks; copying a font asset between projects where the new font has different coverage; specifying a default character excluded from the character regions/CharacterSet.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Type [{0}] must be assignable to Asset or be a Package
• Cannot add an asset with an empty Id
• One of the asset does not match the directory hierarchy.
• Font file not found: {fontPath}
• Font file not found: {fontPath}

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/5f83373fc72a3c2a. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Assets/SpriteFont/Compiler/OfflineRasterizedFontCompiler.cs:191

            // Sort the glyphs
            glyphs.Sort((left, right) => left.Character.CompareTo(right.Character));


            // Check that the default character is part of the glyphs
            if (options.DefaultCharacter != 0)
            {
                bool defaultCharacterFound = false;
                foreach (var glyph in glyphs)
                {
                    if (glyph.Character == options.DefaultCharacter)
                    {
                        defaultCharacterFound = true;
                        break;
                    }
                }
                if (!defaultCharacterFound)
                {
                    throw new InvalidOperationException("The specified DefaultCharacter is not part of this font.");
                }
            }

            return glyphs.ToArray();
        }

        public static List<char> GetCharactersToImport(SpriteFontAsset asset)
        {
            var characters = new List<char>();

            var fontTypeStatic = asset.FontType as OfflineRasterizedSpriteFontType;
            if (fontTypeStatic == null)
                throw new ArgumentException("Tried to compile a dynamic sprite font with compiler for signed distance field fonts");

            // extract the list from the provided file if it exits
            if (File.Exists(fontTypeStatic.CharacterSet))
            {
                string text;

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