Why is this an issue?

Serialization event handlers that don’t have the correct signature will not be called, bypassing augmentations to the automated de/serialization.

A method is designated a serialization event handler by applying one of the following serialization event attributes:

Serialization event handlers take a single parameter of type StreamingContext, return void, and have private visibility.

This rule raises an issue when any of these constraints are not respected.

How to fix it

Code examples

Noncompliant code example

[Serializable]
public class Foo
{
    [OnSerializing]
    public void OnSerializing(StreamingContext context) {} // Noncompliant: should be private

    [OnSerialized]
    int OnSerialized(StreamingContext context) {} // Noncompliant: should return void

    [OnDeserializing]
    void OnDeserializing() {} // Noncompliant: should have a single parameter of type StreamingContext

    [OnSerializing]
    public void OnSerializing2<T>(StreamingContext context) {} // Noncompliant: should have no type parameters

    [OnDeserialized]
    void OnDeserialized(StreamingContext context, string str) {} // Noncompliant: should have a single parameter of type StreamingContext
}

Compliant solution

[Serializable]
public class Foo
{
    [OnSerializing]
    private void OnSerializing(StreamingContext context) {}

    [OnSerialized]
    private void OnSerialized(StreamingContext context) {}

    [OnDeserializing]
    private void OnDeserializing(StreamingContext context) {}

    [OnDeserialized]
    private void OnDeserialized(StreamingContext context) {}
}

Resources

Documentation