TD001 — TemplateData class must be partial

A class marked [BinarySerializedBlob] or [BiometricTemplate] is not declared partial.

The build generates the serialization methods into the same class. It can only do that when the class is partial.

[BiometricTemplate]
public class FingerprintTemplate { }      // missing partial

How to fix it

Add the partial modifier:

[BiometricTemplate]
public partial class FingerprintTemplate
{
    public byte[] TemplateData { get; set; }
}

See biometric enrollment.

If you disagree with a report

Do not suppress it. A wrong report is a bug in the check — report it with the code that triggered it.