OrchardCMS/OrchardCore · error · ArgumentException

Content field name contains invalid characters

Error message

Content field name contains invalid characters

What it means

ContentPartDefinitionBuilder's field builder Build throws ArgumentException when the field name differs from its ToSafeName() form (case-insensitive), i.e. it contains characters disallowed in safe names.

Solutions

1. Sanitize with ToSafeName() before WithField(): builder.WithField(raw.ToSafeName(), ...).
2. Strip invalid characters (keep letters/digits, first char a letter) before building.
3. Validate field names in any custom admin/import UI.

Example fix

// before
partBuilder.WithField("Sales Amount", f => f.OfType<NumericField>()); // throws

// after
partBuilder.WithField("Sales Amount".ToSafeName(), f => f.OfType<NumericField>()); // "SalesAmount"

string safe = rawFieldName.ToSafeName();
bool ok = string.Equals(rawFieldName, safe, StringComparison.OrdinalIgnoreCase);

try
{
    var fieldDef = fieldBuilder.Build();
}
catch (ArgumentException e)
{
    _logger.LogError(e, "Field name '{Name}' contains invalid characters", rawFieldName);
}

When it happens

Trigger: WithField("Sales Amount", ...) or names with dashes/dots/symbols, then the field Build(); field names taken from external sources without sanitization.

Common situations: Field names with spaces from form input, hyphenated names from external schemas, accented characters in names.

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 field name must start with a letter
• Content part name must start with a letter
• Content part name contains invalid characters
• Content type name must start with a letter
• Content type name contains invalid characters

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/ecb3be0efb2e3b06. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.ContentManagement.Abstractions/Metadata/Builders/ContentPartDefinitionBuilder.cs:233

        private readonly string _fieldName;

        public FieldConfigurerImpl(ContentPartFieldDefinition field, ContentPartDefinition part)
            : base(field)
        {
            _fieldDefinition = field.FieldDefinition;
            _fieldName = field.Name;
            _partDefinition = part;
        }

        public override ContentPartFieldDefinition Build()
        {
            if (!char.IsLetter(_fieldName[0]))
            {
                throw new ArgumentException("Content field name must start with a letter", "name");
            }
            if (!string.Equals(_fieldName, _fieldName.ToSafeName(), StringComparison.OrdinalIgnoreCase))
            {
                throw new ArgumentException("Content field name contains invalid characters", "name");
            }

            return new ContentPartFieldDefinition(_fieldDefinition, _fieldName, _settings);
        }

        public override string Name
            => _fieldName;

        public override string FieldType
            => _fieldDefinition.Name;


        public override string PartName
            => _partDefinition.Name;

        public override ContentPartFieldDefinitionBuilder OfType(ContentFieldDefinition fieldDefinition)
        {
            _fieldDefinition = fieldDefinition;

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