AOT not support for DataContractSerializer for serialize and deserialize

[saiganesh-sakthivel]

We have requirement of serializing and deserialize the custom class using the System.Runtime.Serialization.DataContractSerializer with the help of following code in the source code.

Serialize code snippet

annotationsData.Annotations?.Add(new AnnotationDetails { Name = "Test", Age = 30 });

var knownTypes = new List
{
typeof(AnnotationsData),
typeof(AnnotationDetails),
typeof(List),
typeof(string),
typeof(int)
};

DataContractSerializer serializer = new DataContractSerializer(typeof(AnnotationsData), knownTypes);
if (stream != null)
{
serializer.WriteObject(stream, annotationsData);
}

Deserialize code snippet

object? data = null;
var knownTypes = new List
{
typeof(AnnotationsData),
typeof(AnnotationDetails),
typeof(List),
typeof(string),
typeof(int)
};
DataContractSerializer dataContractSerializer = new DataContractSerializer(typeof(AnnotationsData), knownTypes);
if (stream != null && stream.Length > 0)
{
stream.Position = 0;
data = dataContractSerializer.ReadObject(stream);
}

The reported scenario occurs will serialize the class which contains the List when the AOT enable and publish. We have attached the replicate sample in the attachment. Is possible to serialize and deserialize without any crash?

MauiApp2.zip

[vitek-karas]

Please share the way this fails and how did you enable AOT.

[ashok-kuvaraja]

Hi Everyone,

We are encountering an issue when enabling AOT. The serializer.WriteObject() method causes the app to crash in release mode on both Android and Mac platforms—even when AOT is not enabled at the sample level. We've incorporated serializer-related code changes in the source, as it's a dependent package for the sample.

However, we were able to resolve the issue by adding the Preserve attribute alongside the DataContract attributes in the relevant classes.

We are still unsure whether AOT is officially supported on the Android platform. Could you please clarify?

I use below codes to enable AOT in project,

<PropertyGroup Condition="'$(TargetFramework)' == 'net9.0' or '$(TargetFramework)' == 'net9.0-android' or '$(TargetFramework)' == 'net9.0-ios' or '$(TargetFramework)' == 'net9.0-maccatalyst' or '$(TargetFramework)' == 'net9.0-windows10.0.19041.0'">
<IsAotCompatible>true</IsAotCompatible>
</PropertyGroup>

[vitek-karas]

IsAotCompatible doesn't actually enable AOT - it's main use case if for libraries to mark themselves as NativeAOT compatible.
If you use default configuration for Android it will perform partial AOT (not NativeAOT) but it will do trimming of the app. The trimming part is likely what's causing problems - serializers are typically very difficult to make work with trimming unless they're prepared for it.
It would help to know how the app fails - there should be more information in the logs what was the type of the failure.