OrchardCMS/OrchardCore · error · InvalidCastException

Failed casting content to

Error message

Failed casting content to '{typeof(TElement).Name}', check you have registered your content part with AddContentPart?

What it means

ContentExtensions.Get<TElement> throws InvalidCastException when the part/field attached to the content element is not of the requested type TElement. OrchardCore stores parts as typed elements only if the part type was registered; otherwise the stored element cannot be cast to TElement.

Solutions

1. Register the part in your module Startup: services.AddContentPart<MyPart>(); (or AddContentPart<T, TDisplayDriver> etc.).
2. Verify the content item actually has a part/field of that type: use item.Has("MyPart") before calling As<T>().
3. Check the stored part type name matches the class name; if the class was renamed, migrate existing content definitions.
4. Use Get(typeof(TElement)) inspection or item.Parts to see what is actually attached and fix the requested type.

Example fix

// before (no registration)
var part = contentItem.As<MyPart>(); // throws

// after (Startup.cs)
services.AddContentPart<MyPart>();
// usage
var part = contentItem.As<MyPart>();

if (!contentItem.Has("MyPart")) return null;

MyPart GetPartOrNull(ContentItem item) => item.As<MyPart>(); // plus registration check
bool HasPart(ContentItem item) => item is not null && item.Has(nameof(MyPart));

try
{
    var part = contentItem.As<MyPart>();
}
catch (InvalidCastException)
{
    // part not registered or wrong type; log and treat as absent
}

When it happens

Trigger: Calling item.As<MyPart>() (or Get<MyPart>) when MyPart was never registered via services.AddContentPart<MyPart>(), or when the content item actually has a different part/field under that name, or casting a field to a part type (or vice versa).

Common situations: Forgot to register the part in a module Startup.cs, renamed/moved the part class so the stored type name no longer matches, querying a ContentField with Get<TPart>, typo in part name for a different type.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Cannot convert to Int16
• Cannot convert to Int32
• Cannot convert to Int64
• Cannot convert to SByte
• Cannot convert to Float

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/d0bc95aabee24a75. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.ContentManagement.Abstractions/ContentExtensions.cs:47

    /// <param name="contentElement">The <see cref="ContentElement"/>.</param>
    /// <param name="name">The name of the content element.</param>
    /// <typeparam name="TElement">The expected type of the content element.</typeparam>
    /// <returns>The content element instance or. <code>null</code> if it doesn't exist.</returns>
    public static TElement Get<TElement>(this ContentElement contentElement, string name) where TElement : ContentElement
    {
        var result = contentElement.Get(typeof(TElement), name);

        if (result == null)
        {
            return null;
        }

        if (result is TElement te)
        {
            return te;
        }

        throw new InvalidCastException($"Failed casting content to '{typeof(TElement).Name}', check you have registered your content part with AddContentPart?");
    }

    /// <summary>
    /// Gets whether a content element has a specific element attached.
    /// </summary>
    /// <param name="contentElement">The <see cref="ContentElement"/>.</param>
    /// <typeparam name="TElement">The expected type of the content element.</typeparam>
    public static bool Has<TElement>(this ContentElement contentElement) where TElement : ContentElement
    {
        return contentElement.Has(typeof(TElement).Name);
    }

    /// <summary>
    /// Gets a content element by its name.
    /// </summary>
    /// <param name="contentElement">The <see cref="ContentElement"/>.</param>
    /// <param name="contentElementType">The expected type of the content element.</param>
    /// <param name="name">The name of the content element.</param>

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