stride3d/stride · error · YamlException

Unable to find property

Error message

Unable to find property [{0}] in class [{1}]

What it means

After resolving the containing class, PropertyKeyYamlSerializer.ConvertFrom looks up the property name as a public static field via reflection. When GetField returns null it throws YamlException 'Unable to find property [{0}] in class [{1}]'.

Solutions

  1. Confirm the property exists as a public static field on the named class with exact casing
  2. Update the YAML to the current property name after refactors
  3. Ensure the referenced member is static and public (BindingFlags.Public | BindingFlags.Static)
  4. Catch YamlException and provide a default/skip strategy for missing keys

Example fix

// before
key: Stride.Engine.ModelComponent.OldMaterial
// after
key: Stride.Engine.ModelComponent.Material
Defensive patterns

Strategy: try-catch

Validate before calling

var dot = scalar.LastIndexOf('.');
var prop = scalar[(dot+1)..];
bool exists = containingType?.GetField(prop, BindingFlags.Public | BindingFlags.Static) != null;

Try / catch

try { key = serializer.ConvertFrom(ctx, scalar); }
catch (YamlException ex) { /* skip or substitute default property */ }

Prevention

When it happens

Trigger: YAML scalar 'Class.Property' where the class exists but has no public static field with that exact name — misspelled property, property removed/renamed, non-public field, or an instance (non-static) member.

Common situations: Renamed or removed PropertyKey between versions; typos in hand-edited YAML; trying to reference a non-static property; case mismatches.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/04496d14e8e49bd2. Report an issue: GitHub.

Appendix: source

Thrown at sources/core/Stride.Core.Design/Yaml/PropertyKeyYamlSerializer.cs:50

    public override object? ConvertFrom(ref ObjectContext objectContext, Scalar fromScalar)
    {
        var lastDot = fromScalar.Value.LastIndexOf('.');
        if (lastDot == -1)
            return null;

        var className = fromScalar.Value[..lastDot];
        var containingClass = objectContext.SerializerContext.TypeFromTag("!" + className, out _); // Readd initial '!'
        if (containingClass == null)
        {
            throw new YamlException(fromScalar.Start, fromScalar.End, "Unable to find class from tag [{0}]".ToFormat(className));
        }

        var propertyName = fromScalar.Value[(lastDot + 1)..];
        var propertyField = containingClass.GetField(propertyName, BindingFlags.Public | BindingFlags.Static);
        if (propertyField == null)
        {
            throw new YamlException(fromScalar.Start, fromScalar.End, "Unable to find property [{0}] in class [{1}]".ToFormat(propertyName, containingClass.Name));
        }

        return propertyField.GetValue(null);
    }

    protected override void WriteScalar(ref ObjectContext objectContext, ScalarEventInfo scalar)
    {
        // TODO: if ParameterKey is written to an object, It will not serialized a tag
        scalar.Tag = null;
        scalar.IsPlainImplicit = true;
        base.WriteScalar(ref objectContext, scalar);
    }

    public override string ConvertTo(ref ObjectContext objectContext)
    {
        var propertyKey = (PropertyKey)objectContext.Instance;

        return PropertyKeyNameResolver.ComputePropertyKeyName(objectContext.SerializerContext, propertyKey);

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