dotnet/wpf · error · InvalidEnumArgumentException

InvalidEnumArgumentException: invalid SeekOrigin value…

Error message

InvalidEnumArgumentException: invalid SeekOrigin value (nameof(origin))

What it means

SharedStream.Seek validates the SeekOrigin parameter and throws InvalidEnumArgumentException when origin is not one of Begin, Current, or End — i.e. an int was cast to SeekOrigin outside its defined range.

Solutions

Pass only SeekOrigin.Begin, SeekOrigin.Current, or SeekOrigin.End — never a raw cast int.
Validate any externally supplied origin value before casting: if (!Enum.IsDefined(typeof(SeekOrigin), v)) ...
Fix the source of the bad value (saved state, interop marshaling) rather than the call site.
Default to SeekOrigin.Begin when the origin is unknown.

Example fix

// before
stream.Seek(offset, (SeekOrigin)savedOrigin);
// after
if (!Enum.IsDefined(typeof(SeekOrigin), savedOrigin)) throw new InvalidDataException($"bad origin {savedOrigin}");
stream.Seek(offset, (SeekOrigin)savedOrigin);

Defensive patterns

Strategy: type-guard

Validate before calling

// Validate SeekOrigin before calling Seek
bool IsValidSeekOrigin(SeekOrigin origin) => origin is SeekOrigin.Begin or SeekOrigin.Current or SeekOrigin.End;
// for raw ints: Enum.IsDefined(typeof(SeekOrigin), value)

Type guard

static bool IsDefinedSeekOrigin(int v) => v is >= 0 and <= 2; // Begin, Current, End

Try / catch

try
{
    stream.Seek(offset, origin);
}
catch (InvalidEnumArgumentException ex)
{
    throw new InvalidDataException($"Origin must be Begin/Current/End, got {origin}", ex);
}

Prevention

Never cast raw ints to SeekOrigin without Enum.IsDefined
Initialize SeekOrigin variables explicitly (default to SeekOrigin.Begin)
Check interop marshaling of origin values
Use the enum type in your own APIs to get compile-time safety

When it happens

Trigger: Calling sharedStream.Seek(offset, (SeekOrigin)someInt) where someInt is not 0, 1, or 2 — typically an uninitialized variable, bad interop value, or numeric constant mismatch.

Common situations: Interop/P-Invoke code passing raw longs into SeekOrigin casts; deserialization restoring a saved stream position with a corrupt origin field; off-by-one constants (3+).

Understand the failure class

Background: "invalid argument", "unknown mode", "not supported": invalid enum-like argument errors explained — this error's family across 19 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/da759384a57084a8. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/Baml2006/SharedStream.cs:234

        public override long Seek(long offset, SeekOrigin origin)
        {
            long newPosition;
            switch (origin)
            {
                case SeekOrigin.Begin:
                    newPosition = offset;
                    break;

                case SeekOrigin.Current:
                    newPosition = _position + offset;
                    break;

                case SeekOrigin.End:
                    newPosition = _length + offset;
                    break;

                default:
                    throw new InvalidEnumArgumentException(nameof(origin), (int)origin, typeof(SeekOrigin));
            }

            if (newPosition < 0 || newPosition >= _length)
            {
                throw new ArgumentOutOfRangeException(nameof(offset), offset, string.Empty);
            }

            CheckDisposed();

            _position = newPosition;

            return _position;
        }

        public override void SetLength(long value)
        {
            throw new NotSupportedException();
        }

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