JosefNemec/Playnite · error · NotSupportedException

{property.GetType()} property type is not supported in this

Error message

{property.GetType()} property type is not supported in this collection.

What it means

Thrown as NotSupportedException by ItemCollection<TItem>.GetOrGenerate(MetadataProperty) when the provided MetadataProperty is neither a MetadataNameProperty nor a MetadataIdProperty. The collection only knows how to resolve items by name (creating a new instance if not found) or by database ID. Any other MetadataProperty subtype is unsupported.

Source

Thrown at source/Playnite/Database/Collections/ItemCollection.cs:270

        {
            if (property is MetadataNameProperty nameProp)
            {
                var existingItem = this.FirstOrDefault(a => GameFieldComparer.StringEquals(a.Name, nameProp.Name));
                if (existingItem != null)
                {
                    return existingItem;
                }
                else
                {
                    return typeof(TItem).CrateInstance<TItem>(nameProp.Name);
                }
            }
            else if (property is MetadataIdProperty idProp)
            {
                return this[idProp.Id];
            }

            throw new NotSupportedException($"{property.GetType()} property type is not supported in this collection.");
        }

        public virtual IEnumerable<TItem> GetOrGenerate(IEnumerable<MetadataProperty> properties)
        {
            var res = new List<TItem>();
            foreach (var property in properties)
            {
                res.Add(GetOrGenerate(property));
            }

            return res;
        }

        public virtual TItem Add(MetadataProperty property)
        {
            if (property is MetadataNameProperty nameProp)
            {
                return Add(nameProp.Name, GameFieldComparer.FieldEquals);

View on GitHub (pinned to 5911f4e964)

Solutions

1. Ensure all MetadataProperty instances passed to GetOrGenerate are either MetadataNameProperty or MetadataIdProperty.
2. If using a custom MetadataProperty type, convert it to MetadataNameProperty before calling GetOrGenerate.
3. Update Playnite to the latest version if the SDK introduced new property types that should be supported.
4. Add a pre-check: if (property is not MetadataNameProperty and not MetadataIdProperty) convert or skip.

Example fix

// before — passing an unsupported property type
var item = collection.GetOrGenerate(myCustomProperty);

// after — normalize to a supported type before calling
MetadataProperty normalized = myCustomProperty switch
{
    MetadataNameProperty np => np,
    MetadataIdProperty ip => ip,
    _ => new MetadataNameProperty(myCustomProperty.ToString())
};
var item = collection.GetOrGenerate(normalized);

if (property is not MetadataNameProperty and not MetadataIdProperty)
{
    logger.Warn($"Unsupported property type {property.GetType()} for GetOrGenerate.");
    property = new MetadataNameProperty(property.ToString());
}

static bool IsSupportedMetadataProperty(MetadataProperty property)
{
    return property is MetadataNameProperty or MetadataIdProperty;
}

When it happens

Trigger: A metadata plugin or import process passes a custom MetadataProperty subclass to GetOrGenerate. The SDK was extended with new MetadataProperty types but the collection was not updated. A serialized MetadataProperty deserialized into an unexpected concrete type.

Common situations: A third-party metadata provider returns a proprietary MetadataProperty subclass. A plugin SDK version mismatch where newer property types are passed to an older collection implementation. Incorrect serialization/deserialization that loses the concrete type information.

Related errors

• Cannot add file to database, file not found.
• Emulator not found.
• BSON type not supported
• Database path cannot be empty.
• Can't write to "{DatabasePath}" folder.

AI-assisted analysis of JosefNemec/Playnite@5911f4e964 (2026-08-13). Data as JSON: /api/errors/a741d9f5ca221eba. Report an issue: GitHub.