CodeGen issue when upgrading from 1.3.1 to 1.5.1

Description

After upgrading from 1.3.1 to 1.5.1 I get this error in the console

Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP: (0,0): error  - System.NullReferenceException: Object reference not set to an instance of an object.||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.GenerateVariableInitialization(TypeDefinition type)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.ProcessNetworkBehaviour(TypeDefinition typeDefinition, String[] assemblyDefines)||   at System.Collections.Generic.List`1.ForEach(Action`1 action)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.Process(ICompiledAssembly compiledAssembly)   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.GenerateVariableInitialization(TypeDefinition type)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.ProcessNetworkBehaviour(TypeDefinition typeDefinition, String[] assemblyDefines)||   at System.Collections.Generic.List`1.ForEach(Action`1 action)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.Process(ICompiledAssembly compiledAssembly)

Reproduce Steps

I don’t have any reproduction steps other than the package upgrade but I don’t know which part of our codebase is triggering this. The project is huge and we probably cannot send it due to company policy.

Is there any way I can get a better stack trace?

Actual Outcome

The codegen has this exception and the project cannot run.

Expected Outcome

A smooth upgrade or an error message saying what serialization code should change.

Environment

• OS: [Windows 10]
• Unity Version: [2022.3]
• Netcode Version: [1.5.1]

Additional Context

I’ll try to find what part of our serialization code might be causing this but it would be good if there was a way to see where it breaks or what serialization code-gen changes happend. And again this is the error log

Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP: (0,0): error  - System.NullReferenceException: Object reference not set to an instance of an object.||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.GenerateVariableInitialization(TypeDefinition type)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.ProcessNetworkBehaviour(TypeDefinition typeDefinition, String[] assemblyDefines)||   at System.Collections.Generic.List`1.ForEach(Action`1 action)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.Process(ICompiledAssembly compiledAssembly)   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.GenerateVariableInitialization(TypeDefinition type)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.ProcessNetworkBehaviour(TypeDefinition typeDefinition, String[] assemblyDefines)||   at System.Collections.Generic.List`1.ForEach(Action`1 action)||   at Unity.Netcode.Editor.CodeGen.NetworkBehaviourILPP.Process(ICompiledAssembly compiledAssembly)

I noticed one code-gen feature is added for initialization and that might be the cause? I assume there is no regression in the other serialization codes of course.

[ashkan-saeedi-mazdeh]

I found out what was the problem in our case. We had a class Singleton<T>:NetworkBehaviour class which we were not even using and it was causing this.

[ashkan-saeedi-mazdeh]

I’ll close this since it is a duplicate.