Debugger shows <incomplete type> for any class deriving from Unreal base classes

Hello Jordan,

Thank you for contacting Rider support. That looks weird. Would you mind sharing Rider logs with me, so that I can take a deeper look?

• Go to Help | Diagnostic tools | Choose Trace Scenarios;
• Enable the trace scenario for Debugger;
• Reproduce the issue;
• Collect the full log bundle via Help | Collect Logs and Diagnostic Data;
• Disable the trace scenarios enabled;
• Attach the resulting log bundle to this ticket or upload it to our server and share the ID.

Thank you in advance and have a great day!

Hi Dmitry,

I uploaded the generated logs.  Upload ID: 2025_04_23_bFyseC4ayEGmyFdYBcZdaR 

Let me know if you need anything else!

Hello Jordan,

Thank you for the details shared. Would you mind checking if switching configuration to DebugGame helps?

Have a nice day!

Ah, I just noticed you already run DebugGame. Apologies. Will double-check on Linux and get back.

Just an update of a few things I've tried without success in resolving this:

1. Update Rider from 2025.1 to 2025.1.1
2. Uninstall Rider via the Toolbox App and re-install
3. Delete the Intermediate and Binaries folders in my project layout; do full project rebuild
4. Launch Rider via the Unreal Editor and Attach to Process

All of these resulted in the same <incomplete type> issue.  I could try installing Rider via the standalone installer, but not sure how that would help.  If you think installing an older version of Rider would help I can try that. 

OK I did a simpler test to exclude my existing project and plugins from the mix:

1. Create a new blank C++ project via the Editor using the binaries for UE 5.5.4 from Epic on Ubuntu 24.04.2 LTS
2. Create a new C++ class deriving from GameModeBase named TestGameModeBase
3. Add the below code for the .cpp and .h file
4. Compile and launch the editor in DebugGame configuration through Rider
5. In the Unreal Editor menu Edit → Project Settings → Maps & Modes → Default GameMode set TestGameModeBase under Default GameMode

6. Set breakpoint in ATestGameModeBase::SpawnDefaultPawnAtTransform_Implementation, hit Alt+P to play in editor and investigate the this variable showing <incomplete type> and an invalid value for numberConnectedPlayers that was set in InitGame.

   

TestGameModeBase.h:

UCLASS()
class TESTBLANK_API ATestGameModeBase : public AGameModeBase
{
	GENERATED_BODY()
public:
	virtual void InitGame(const FString& mapName, const FString& options, FString& errorMessage) override;
	virtual APawn* SpawnDefaultPawnAtTransform_Implementation(AController* NewPlayer, const FTransform& SpawnTransform) override;
protected:

	UPROPERTY()
	int numberConnectedPlayers = 0;
};

TestGameModeBase.cpp:

#include "TestGameModeBase.h"
#include <Engine/World.h>
#include <GameFramework/GameStateBase.h>
#include <GameFramework/PlayerState.h>

void ATestGameModeBase::InitGame(const FString& mapName, const FString& options, FString& errorMessage)
{
	Super::InitGame(mapName, options, errorMessage);
	numberConnectedPlayers = 0;
}

APawn* ATestGameModeBase::SpawnDefaultPawnAtTransform_Implementation(AController* NewPlayer, const FTransform& SpawnTransform)
{
	APlayerController* playerController = Cast<APlayerController>(NewPlayer);
	ensure(playerController);
	AGameStateBase* gameState = Cast<AGameStateBase>(GetWorld()->GetGameState());

	if (GetLocalRole() == ROLE_Authority)
	{
		int brk = 0;
		brk++;
	}
	return Super::SpawnDefaultPawnAtTransform_Implementation(NewPlayer, SpawnTransform);
}

Hi Dmitry,

I tried a few more things to try and get debugging working properly on Linux, but have not had any success.  I thought that because I had once run the Setup scripts from an Unreal source download (to setup the toolchain) that it could have affected using Rider with the UE binary version so I did the following to remove any potential cached settings from Epic:

• delete /Home/.epic
• delete /Home/.config/Epic
• delete /Home/.config/Unreal Engine
• delete /Home/.config/unrealEngine
• Deleted the Engine install of the RiderLink plugin
• Deleted all project intermediate folders
• Run the 5.5.4 Unreal Editor binary from my minimal test project, set Rider as the source editor, open the Rider uproject from the editor.
• Shutdown the editor, Rebuild the project via Rider
• Do a fresh install of the RiderLink plugin to the Game instead of Engine this time

With all of that I still have the same debugging issue.  I can attempt a full source build to see if that resolves the issue, but I'd rather not yet since I'm still updating the engine on every release for my project.

Edit: I also tried using a different version of Rider (2024.3.7) to see if that changed anything, but no luck.

Building the engine from source now gets me full debugging symbols in:

• Debug | Game | Linux
• DebugGame | Game | Linux
• Development | Game | Linux

I do not have valid symbols (the original issue of <incomplete type>) for objects deriving from UObject/AActor/etc in:

• Debug | Editor | Linux
• DebugGame | Editor | Linux
• Development | Editor | Linux

That unblocks a good amount of Linux development for me now at least, but I am rather surprised that I have no debug symbols in Debug | Editor even.

Hello Jordan,

Thank you for the details shared. Apologies for taking that long to respond. Once I have a fully-fledged update for you, I'll be back. 

In short: I reproduced the issue with binary UE 5.5 on Ubuntu. I am yet to verify UE 5.3.2 (one colleague confirmed, the issue doesn't persist for him with the binary 5.3.2 engine).

I am glad to hear you are somewhat unblocked with development now. This case isn't forgotten, and I'll be back once I have more details.

Have a nice day!

Thanks for the update Dmitry!

I ended up buying a Rider license so I still get to experience this issue daily :)

Any updates on this at all?  I do plan to update to 5.6 once the first non-preview version is released.  I'm curious if you found out of it's a 5.5 only issue or not.

Hello Jordan,

There is indeed something, and it is unlikely related to UE version. At the moment, I reported this issue:
RIDER-126346 Debugger reports "" for base UObject member. Can expand almost nothing. Only adresses are shown.

Next a developer will take a look. Once we have any news, I'll share an update on the issue page.

If there is anything else I can assist you with, please tell me.

Thank you for reporting this and have a nice day!

Thanks for the update Dmitry, I'll follow the reported issue for any updates.