OrchardCMS/OrchardCore · error · ArgumentException

Content type name contains invalid characters

Error message

Content type name contains invalid characters

What it means

ContentDefinitionService.AddTypeAsync validates the proposed content type name: it must start with an ASCII letter and must equal its ToSafeName() form (case-insensitive). If the name contains characters that would be altered or stripped by the safe-name normalization (spaces, digits leading, symbols, non-ASCII), an ArgumentException is thrown rather than silently mutating the caller's name.

Solutions

1. Sanitize the name with the .ToSafeName() string extension before calling AddTypeAsync.
2. Ensure the name starts with an ASCII letter and contains only letters, digits, and hyphens (no spaces or symbols).
3. If the user-facing label differs from the technical name, pass a safe technical name and keep the label in the type's display name settings.

Example fix

// before
await contentDefinitionService.AddTypeAsync("Product Category", template => { });
// after
await contentDefinitionService.AddTypeAsync("Product Category".ToSafeName(), template => { }); // "ProductCategory"

// C#
static bool IsValidContentTypeName(string name) =>
    !string.IsNullOrEmpty(name)
    && char.IsAsciiLetter(name[0])
    && string.Equals(name, name.ToSafeName(), StringComparison.OrdinalIgnoreCase);
// call AddTypeAsync only if IsValidContentTypeName(name)

static bool IsSafeName(string name) =>
    !string.IsNullOrWhiteSpace(name) && name == name.ToSafeName();

try
{
    await contentDefinitionService.AddTypeAsync(name, configure);
}
catch (ArgumentException ex)
{
    logger.LogWarning(ex, "Invalid content type name: {Name}", name);
}

When it happens

Trigger: Calling IContentDefinitionService.AddTypeAsync(name, ...) with a name that does not survive ToSafeName(), e.g. "My Type!", "1Widget", "Type-Ünï", or containing '/' or '.'.

Common situations: Deriving a type name from user input, a file name, or a display label; generating type names programmatically from localized strings; building type names by concatenation with separators.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Content type name must start with a letter
• The 'displayName' can't be null or empty.
• File path must be a non-empty string.
• Unable to create a safe index prefix for AI Search…
• Content part name must start with a letter

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/23ccfe234f5ca12c. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.ContentTypes/Services/ContentDefinitionService.cs:68

    {
        if (string.IsNullOrWhiteSpace(displayName))
        {
            throw new ArgumentException($"The '{nameof(displayName)}' can't be null or empty.", nameof(displayName));
        }

        if (string.IsNullOrWhiteSpace(name))
        {
            name = await GenerateContentTypeNameFromDisplayNameAsync(displayName);
        }
        else
        {
            if (!char.IsAsciiLetter(name[0]))
            {
                throw new ArgumentException("Content type name must start with a letter", nameof(name));
            }
            if (!string.Equals(name, name.ToSafeName(), StringComparison.OrdinalIgnoreCase))
            {
                throw new ArgumentException("Content type name contains invalid characters", nameof(name));
            }
        }

        while (await _contentDefinitionManager.LoadTypeDefinitionAsync(name) is not null)
        {
            name = VersionName(name);
        }

        var contentTypeDefinition = new ContentTypeDefinition(name, displayName);

        await _contentDefinitionManager.StoreTypeDefinitionAsync(contentTypeDefinition);

        // Ensure it has its own part.
        await _contentDefinitionManager.AlterTypeDefinitionAsync(name, builder => builder.WithPart(name));
        await _contentDefinitionManager.AlterTypeDefinitionAsync(name, cfg =>
        {
            cfg.Creatable()
                .Draftable()

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