IL2CPP runtime Error in plugins

hello! i have a project that uses System.Text.Json nuGet package dlls, i put .net2standard dlls in plugin folder. when i build for android with mono it works fine, but when i change to il2cpp it doesn't work. in build it throw a runtime error saying it can't find constructor of jsonserialization class.
i don't have any clue what is the problem! any help appreciated! Thanks in advance!

 

Log
Scene SampleScene is loaded
UnityEngine.Debug:Log(Object)
Reporter:_OnLevelWasLoaded(Scene, LoadSceneMode)
UnityEngine.SceneManagement.SceneManager:Internal_SceneLoaded(Scene, LoadSceneMode)

Exception
MissingMethodException: Constructor on type 'System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1[[Sample+req, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]]' not found.
System.RuntimeType.CreateInstanceImpl (System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes, System.Threading.StackCrawlMark& stackMark) (at <00000000000000000000000000000000>:0)
System.Activator.CreateInstance (System.Type type, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture, System.Object[] activationAttributes) (at <00000000000000000000000000000000>:0)
System.Activator.CreateInstance (System.Type type, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder binder, System.Object[] args, System.Globalization.CultureInfo culture) (at <00000000000000000000000000000000>:0)
System.Text.Json.Serialization.Converters.ObjectConverterFactory.CreateConverter (System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.Serialization.JsonConverterFactory.GetConverterInternal (System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializerOptions.GetConverter (System.Type typeToConvert) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializerOptions.DetermineConverter (System.Type parentClassType, System.Type runtimePropertyType, System.Reflection.MemberInfo memberInfo) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonClassInfo.GetConverter (System.Type type, System.Type parentClassType, System.Reflection.MemberInfo memberInfo, System.Type& runtimeType, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonClassInfo..ctor (System.Type type, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializerOptions.GetOrAddClass (System.Type type) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializerOptions.GetOrAddClassForRootType (System.Type type) (at <00000000000000000000000000000000>:0)
System.Text.Json.MemberAccessor..ctor () (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializer.ReadCore[TValue] (System.Text.Json.Utf8JsonReader& reader, System.Type returnType, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializer.Deserialize[TValue] (System.String json, System.Type returnType, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
System.Text.Json.JsonSerializer.Deserialize[TValue] (System.String json, System.Text.Json.JsonSerializerOptions options) (at <00000000000000000000000000000000>:0)
Sample.Start () (at <00000000000000000000000000000000>:0)

 

I disabled striping. My class doesn't have constructor. But AFAIK c# defines a default constructor if you don't declare any.

 

I don't understand "Sample+req". Could It be a problem that I defined two classes in one file? Tommarow I will put each class in a separate file.

 

They are not nested, they are just writen in same file. I will post my code tomorrow. But anyway it works fine in editor and in mono build for Android but it doesn't with il2cpp.

EDIT: yes they were nested! i were careless!

 

this is my code:

Code (CSharp):

1. using UnityEngine;
2. using System.Text.Json;
3. using UnityEngine.UI;
4.  
5. public class Sample : MonoBehaviour
6. {
7.     public Text text;
8.     public TextAsset textAsset;
9.     private void Start()
10.     {
11.         req rq = JsonSerializer.Deserialize<req>(textAsset.text);
12.         text.text = rq.type;
13.     }
14.     class req
15.     {
16.         public string type { get; set; }
17.         public string[] product_ids { get; set; }
18.         public string[] channels { get; set; }
19.     }
20. }
21.  

in the text asset there is this content:

Code (CSharp):

1. {
2.     "type": "subscribe",
3.     "product_ids": [
4.         "ETH-USD",
5.         "ETH-EUR"
6.     ],
7.     "channels": [
8.         "level2",
9.         "heartbeat"
10.     ]
11. }

it is a very simple json parser. i wrote this to test if il2cpp works fine or not. because i read that i must build with it to have x64 build for google play store because it is mandatory.

 

Thank you all friends for your help. I will discuss the source of the problem and solution:
1- as @JoshPeterson said "it is not possible to disable managed code stripping for an IL2CPP build from the player settings". i were careless and misinterpreted "strip engine code" option as "strip code".
2- the problem was in code striping.
3- for some nonsense reason, we can't disbale code striping in il2cpp mode.
4- my exception was very simple:

Code (CSharp):

1. Exception
2. MissingMethodException: Constructor on type 'System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1[[Sample+req, Assembly-CSharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]]' not found.

it is obvious that problem is in System.Text.Json.Serialization
5- i created a link.xml file with this content

Code (CSharp):

1. <linker>
2.   <assembly fullname="System.Text.Json"/>
3. </linker>

6- problem solved! So far!

it was a mere 10 line project and my first attempt to test il2cpp. after some investigation and reading https://docs.unity3d.com/Manual/scripting-backends.html I found that I will have some problem with my main project because it is a multiplayer online game and it havily depends on serialization and therefore reflection and generics and sometimes dynamic keyword. and these technics depends on JIT but il2cpp is AOT and i wil have a hard time to migrate from mono to il2cpp.

Thank you again for your help

 

Anyway It will not do a massive harm if you could disable it and see the results. Maybe it's size would be OK. Also when I disable Stripping in mono my Apk is not that big. Albeit I don't khow if il2cpp without Stripping results with the same size as mono but anyway I believe that having options and choices is not bad in this matter!
And also there is a solution for disabling Stripping but it is not straightforward. You must add attributes for your assemblies and add a link.xml for third-parties. That's it.

 

Fortunately my problem is solved and I know the solution thanks to your advises! I hope you add 64 bit support to mono if it is possible!