UWP DataContractSerializer fails to load configuration section

I am trying to serialize a simple class in a UWP app using the following code:

Code (CSharp):

1. var serializer = new DataContractSerializer(typeof(Data));
2. using (var stream = new MemoryStream())
3. using (var writer = XmlDictionaryWriter.CreateBinaryWriter(stream))
4. {
5.     serializer.WriteObject(writer, new Data() { Foo = 42 });
6. }

However, no matter what I seem to do with the data I run into this exception at runtime:

Guessing from reference source it looks like the exception happens as the DataContractSerializer tries to read a section from the ConfigurationManager.

http://referencesource.microsoft.co...ializerSection.cs,4e6898d0a7262dad,references

However, in UWP the ConfigurationManager no longer exists. I ran into this problem when compiling both .NET 3.5 and .NET 4.6. Has anyone else run into a similar issue? Has anyone else been able to get the DataContractSerializer to work for UWP?

 

I'm using the DataContractSerializer to serialize some game state and send it over the wire as a binary blob.

EDIT: I will set up a repro and file a bug.

 

I ran into the same issue when deploying an Android app using the 4.6 .NET runtime and Unity 2017.3f3. Works ok in the editor on Windows.

ConfigurationErrorsException: Failed to load configuration section for dataContractSerializer.

• at System.Runtime.Serialization.Configuration.DataContractSerializerSection.UnsafeGetSection () [0x00026] in <3355504862ba4e7f92c25c91d98a6780>:0
• at System.Runtime.Serialization.DataContract.get_ConfigSection () [0x00007] in <3355504862ba4e7f92c25c91d98a6780>:0
• at System.Runtime.Serialization.DataContract.LoadKnownTypesFromConfig (System.Type type, System.Collections.Generic.Dictionary`2[TKey,TValue] typesChecked, System.Collections.Generic.Dictionary`2[System.Xml.XmlQualifiedName,System.Runtime.Serialization.DataContract]& knownDataContracts) [0x00000] in <3355504862ba4e7f92c25c91d98a6780>:0
• at System.Runtime.Serialization.DataContract.ImportKnownTypeAttributes (System.Type type, System.Collections.Generic.Dictionary`2[TKey,TValue] typesChecked, System.Collections.Generic.Dictionary`2[System.Xml.XmlQualifiedName,System.Runtime.Serialization.DataContract]& knownDataContracts) [0x00228] in <3355504862ba4e

 

I have the same problem, this time with WebGL build. I am using
DataContractJsonSerializer instead if JsonUtility as JsonUtility does not support serialization of decimals nor
cutstom ISerializables, and I do not like how it serializes floats (e.g. 1.4999999999999999 instead of 1.5). I'm using JSON instead of binary serialization because I want human readable output.

DataContractJsonSerializer works fine in editor, but in WebGL build construction of
DataContractJsonSerializer throws

Code (CSharp):

1. ConfigurationErrorsException: Failed to load configuration section for dataContractSerializer.

Nothing else is needed to reproduce the problem.
If I will be unable to fix it, I'll just have to switch to ints.

 

We are having this also, please vote for the issue in the Unity bug tracker - its blocking our first Android release! :-O

https://issuetracker.unity3d.com/is...figuration-section-for-datacontractserializer

 

Running into exact same issue. any news or update?

 

Will you put some of that information here: https://issuetracker.unity3d.com/is...figuration-section-for-datacontractserializer

the current state of closed with "By Design" with no comment from Unity is extremely frustrating especially previously it was "Workaround possible" with also no comment about how to work around it.

Unfortunately for my project its totally not possible to to move to .NET 2 from 4 but waiting until 2018.3 is an option. Will this be fixed in the 2018.3.1 beta?

Edit: Just found this page which seems related: https://docs.unity3d.com/Manual/IL2CPP-BytecodeStripping.html

 

Thanks so much for adding it! <3 And great news we were able to make some minor changes and get it working with .Net 2 so all is good for us now :-D

If I may make a suggestion - once something reported in the forums is made into a bug report have the form page "locked" and link to the bug report and have further discussion of it done on the bug report (which would also link to the forum post that triggered the bug report) - that way all the information is all in one place and no one has to worry about a bug being closed as "wont fix" or even left as "workaround possible" with further info about it back in a forum post.

It was a little on the slow side getting info from Unity on the workaround but we definately appreciate you guys fixing the bug and finally posting the workaround info

 

Ok well...... everything was working until we tested on WebGL.

This bit of code:

Code (CSharp):

1.         string output = "";
2.         StageJsonDelegate stage = new StageJsonDelegate(BlockManager.Instance);
3.         StageCollection collection = new StageCollection(stage);
4.         CultureInfo currentCulture = Thread.CurrentThread.CurrentCulture;
5.         Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
6.         try
7.         {
8.             MemoryStream ms = new MemoryStream();
9.             DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(StageCollection));
10.             XmlDictionaryWriter writer = JsonReaderWriterFactory.CreateJsonWriter(ms, Encoding.UTF8, true, false);
11.             serializer.WriteObject(writer, collection);
12.             writer.Flush();
13.             output += Encoding.UTF8.GetString(ms.ToArray());
14.         }
15.         catch (System.Exception exception)
16.         {
17.             LogController.Log(exception.ToString());
18.         }
19.         finally
20.         {
21.             CurrentState = State.Idle;
22.             Thread.CurrentThread.CurrentCulture = currentCulture;
23.         }

the line: serializer.WriteObject(writer, collection); is thowing:

Code (CSharp):

1. System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.ExecutionEngineException: Attempting to call method 'System.Runtime.Serialization.XmlObjectSerializerWriteContext::IncrementCollectionCountGeneric<System.Collections.Generic.KeyValuePair`2[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]>' for which no ahead of time (AOT) code was generated.
2.  
3. --- End of inner exception stack trace ---
4.  
5. at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <00000000000000000000000000000000>:0

I think is having trouble serializing a Dictionary (but this is just a guess):

Code (CSharp):

1. [DataMember(Name="Properties",Order = 100)]
2. public Dictionary<string, string> Properties

AFAIK there is no way to force AOT generation for a non-public method like this correct?

 

Ok so the good news: I can confirm the linker xml thing works in 2018.3beta for .NET4

The bad news: we still get the same AOT exception when trying to serialize

*Edit* update: as expected this error is occuring on all IL2CPP platforms

Assuming I'm reading this exception right and its an error in serializing a Dictionary<string,string> - In worst case we can probably create some kind of custom string dictionary class to work around it in our code, though I imagine serializing dictionaries is something Unity would like to fix.

 

It is definately related to serializing a Dictionary<string,string>

One thing that did not work: using the

Code (CSharp):

1. DataContractJsonSerializer(Type, IEnumerable<Type>)

version of DataContractJsonSerializer and passing a list of types including Dictionary<string,string>

too bad that would have been nice and easy! it threw the same exception.

Disabling the Dictionary<string,string> field results in serialization working fine, so its just this one type messing things up.

On a whim I tried changing the field to a List<KeyValuePair<string,string>> but got the same results. (expected since I think its the KeyValuePair part that is messing everything up)

 

Ok looks like we have been able to create a workaround by changing our code to use a custom class in a list instead of dictionary. I do believe the code below allows us to keep the same JSON format while working around the AOT error (we are still testing though)

Old code:

Code (CSharp):

1. [DataMember(Name = "Properties", Order = 100)]
2. public Dictionary<string, string> Properties {
3.       get { return _block.Properties; }
4.  }

New code:

Code (CSharp):

1. [DataMember(Name="Properties",Order = 100)]
2.     public List<PropertyJsonDelegate> Properties
3.     {
4.         get
5.         {
6.             Debug.Assert(_block != null);
7.             List<PropertyJsonDelegate> test = new List<PropertyJsonDelegate>();
8.             foreach(KeyValuePair<string,string> item in _block.Properties)
9.             {
10.                 test.Add(new PropertyJsonDelegate(item));
11.             }
12.             return test;
13.         }
14. }

Code (CSharp):

1. [DataContract(Name="Property")]
2. public class PropertyJsonDelegate
3. {
4.     [DataMember]
5.     public string Key;
6.     [DataMember]
7.     public string Value;
8.  
9.     public PropertyJsonDelegate(KeyValuePair<string,string> value)
10.     {
11.         Key = value.Key;
12.         Value = value.Value;
13.     }
14. }

 

I was running into this issue in Unity 2019.1.0f2 with .NET 4.x Api Compatibility Level selected in Player settings. Even without reverting to .NET 2.0, adding the specified `assembly` element to my link.xml as described above fixed the problem for me.

 

I had this issue in 2019.1.2f1
Work Around:
I Replaced

using System.Runtime.Serialization;

with

using System.Runtime.Serialization.Formatters.Binary;

and used the Binary formatter instead to get basically the same functionality. Because the link.xml wasn't working as a fix for my android target platform build.

 

i had this issue when i m trying to save my game data. I have used linker. when i am loading file from json it works fine at saving time its shows below error:
07-01 13:05:39.463 27881-27952/com.abcd.runner I/Unity: System.ExecutionEngineException: Attempting to call method 'System.Runtime.Serialization.XmlObjectSerializerWriteContext::IncrementCollectionCountGeneric<System.Collections.Generic.KeyValuePair`2[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]>' for which no ahead of time (AOT) code was generated.
at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <00000000000000000000000000000000>:0
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0
at System.Runtime.Serialization.Json.JsonFormatWriterInterpreter.WriteCollection (System.Runtime.Serialization.CollectionDataContract collectionContract) [0x00000] in <00000000000000000