dotnet/wpf · error · ArgumentException

InvalidDataInISF

Error message

InvalidDataInISF

What it means

While decoding extended properties from an ISF stream, converting the persisted bytes back to a char or char[] threw ArgumentException (bad character data), so the serializer wraps it in a new ArgumentException with SR.InvalidDataInISF. This indicates the ISF payload is corrupt or was not produced with matching type metadata. The original exception is preserved as InnerException.

Solutions

1. Validate the ISF source file/stream integrity before loading
2. Remove or re-save the offending ExtendedProperty before serializing the ink again
3. Inspect ex.InnerException for the underlying decode failure
4. Regenerate the ISF from the original ink data if available

Example fix

// before
strokeCollection = new StrokeCollectionReader(isfStream).GetStrokeCollection(); // throws on corrupt data
// after
try
{
    strokeCollection = new StrokeCollectionReader(isfStream).GetStrokeCollection();
}
catch (ArgumentException ex) when (ex.InnerException != null)
{
    // log ex.InnerException; fall back to re-saving or skipping the bad stroke
}

try { strokes = new StrokeCollection(isfStream); }
catch (ArgumentException ex) when (ex.Message.Contains("ISF")) { Log(ex.InnerException); isfStream.Seek(0, SeekOrigin.Begin); /* salvage path */ }

When it happens

Trigger: Reading a stroke's ExtendedProperties from ISF whose declared type is char/char[] but the byte payload is not a valid UTF-16 char sequence — e.g. odd byte counts, truncated data, or data written by a non-WPF producer.

Common situations: Hand-edited or third-party-generated ISF; files truncated in transfer; cross-version/cross-platform ISF interchange where the extended property type table disagrees with the payload.

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.

Related errors

• Drawing Attribute tag embedded in ISF stream does not match…
• Invalid ISF data
• Invalid PenTip value found in ISF stream
• Invalid size specified
• ISF Operation Failed

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/ca3a12dda101fb47. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationCore/MS/internal/Ink/InkSerializedFormat/CustomAttributeSerializer.cs:949

                                                break;
                                            }
                                            case (VarEnum.VT_DATE)://7
                                            {
                                                DateTime data = (DateTime)value;
                                                writer.Write(data.ToOADate());
                                                break;
                                            }
                                            default:
                                            {
                                                Debug.Fail("Missing case statement!");
                                                break;
                                            }
                                        }
                                    }
                                    catch (ArgumentException ex)
                                    {
                                        //catches bad char & char[]
                                        throw new ArgumentException(SR.InvalidDataInISF, ex);
                                    }
                                    catch (OverflowException ex)
                                    {
                                        //catches bad DateTime
                                        throw new ArgumentException(SR.InvalidDataInISF, ex);
                                    }
                                }
                            }
                            break;
                        }
                        //do nothing in the default case...
                    }
                }
                return;
            }
        }
        #endregion // Key/Value pair validation helpers

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