stride3d/stride · error · FormatException

Unable to parse the input string.

Error message

Unable to parse the input string.

What it means

ItemId.Parse converts a string (typically a GUID in the canonical form produced by ItemId/ Guid) into an ItemId. It delegates to TryParse and, if parsing fails, throws FormatException. The library throws this when the input string is not a valid, fully-formed identifier.

Solutions

1. Switch to ItemId.TryParse and handle the false return instead of catching FormatException.
2. Verify the input string is a valid GUID in the exact format the library emits (32 hex digits / 'N' or 'D' form) and trim whitespace.
3. Fix the source data (config, YAML asset, CLI arg) to contain the correct id string.
4. Regenerate the id with ItemId.New() if the original value is unrecoverable.

Example fix

// before
var id = ItemId.Parse(userInput);

// after
if (!ItemId.TryParse(userInput?.Trim(), out var id))
    throw new ArgumentException($"'{userInput}' is not a valid ItemId", nameof(userInput));

if (string.IsNullOrWhiteSpace(input) || !Guid.TryParseExact(input.Trim(), "D", out _))
    throw new ArgumentException("Not a valid ItemId string", nameof(input));
var id = ItemId.Parse(input.Trim());

bool IsValidItemId(string? s) => !string.IsNullOrWhiteSpace(s) && Guid.TryParseExact(s.Trim(), "D", out _);

try { var id = ItemId.Parse(input); }
catch (FormatException) { /* fall back to ItemId.New() or surface a user error */ }

When it happens

Trigger: Calling ItemId.Parse with a null, empty, malformed, or non-GUID string — e.g. a truncated id, a string with braces/extra whitespace the parser does not accept, or user-supplied text instead of an id.

Common situations: Reading ids from configuration files or command-line arguments where the value was copied incorrectly; parsing ids from older asset files written in a different format; passing an empty string from an unset environment variable.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

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

Related errors

• The string does not match the expected format.
• A part Id cannot be empty.
• Could not parse a valid version from
• Could not parse semantic index from the semantic name
• Couldn't handle operand kind

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/c4483abbd4f89147. Report an issue: GitHub.

Appendix: source

Thrown at sources/assets/Stride.Core.Assets/Reflection/ItemId.cs:57

    /// <summary>
    /// Generates a new random <see cref="ItemId"/>.
    /// </summary>
    /// <returns></returns>
    public static ItemId New()
    {
        return new ItemId(ObjectId.New());
    }

    /// <summary>
    /// Parses an <see cref="ItemId"/> from a string.
    /// </summary>
    /// <param name="input">The input string to parse.</param>
    /// <returns>An <see cref="ItemId"/> corresponding to the parsed string.</returns>
    /// <exception cref="FormatException">The given string cannot be parsed as an <see cref="ItemId"/>.</exception>
    public static ItemId Parse(string input)
    {
        if (!TryParse(input, out var itemId))
            throw new FormatException("Unable to parse the input string.");

        return itemId;
    }

    /// <summary>
    /// Attempts to parse an <see cref="ItemId"/> from a string.
    /// </summary>
    /// <param name="input">The input string to parse.</param>
    /// <param name="itemId">The resulting <see cref="ItemId"/>.</param>
    /// <returns>True if the string could be successfully parsed, False otherwise.</returns>
    public static bool TryParse(string input, out ItemId itemId)
    {
        if (ObjectId.TryParse(input, out var objectId))
        {
            itemId = new ItemId(objectId);
            return true;
        }
        itemId = Empty;

View on GitHub (pinned to 96fad776d2)