More then two Vive Trackers cause crash

Unreal Editor crashes if two Motion Controllers and more then two Vive Trackers are enabled. It happens in any project, including empty non-VR projects. If controllers and trackers were enabled before launch, Editor crashes at start. If Motion Controllers are disabled on launch and turned on later, editor works for a some time, but can crash at any moment. The problem exists in a 4.17 Preview 2.


[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Controller role for device 3 is 2 (invalid=0, left=1, right=2).

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Warning: Controller device 3 is being assigned to its prefered role ‘right’.

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Controller role for device 4 is 1 (invalid=0, left=1, right=2).

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Putting controller 4 on the left hand because there is already a controller for the right.

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Tracker device 5 is being assigned unreal hand: Special 1, for player 0

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Tracker device 6 is being assigned unreal hand: Special 2, for player 0

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Tracker device 7 is being assigned unreal hand: Special 3, for player 0

[2017.07.23-20.44.32:523][ 0]LogSteamVRController: Tracker device 8 is being assigned unreal hand: Special 4, for player 0

[2017.07.23-20.44.32:526][ 0]LogWindows: Windows GetLastError: Operation completed successfully. (0)

Same for me and same happens with 4.16.

Hello YuriNK,

Thank you for the information above. I have a few questions for you that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Can you provide your complete call stack including your machine ID?
  2. Could you provide your complete logs?
  3. Are you using any third party plugins?
  4. Could you provide any changes to settings that may be involved with this issue?

Hi, I have created issue here with more information I could get with quick check with debugger: Editor crashes with Vive trackers. - XR Development - Unreal Engine Forums

Actually, we were trying to implement our own plugin for different projects with some additional functionality related to motion tracking. When we’ve got Trackers (5 pcs) shipping, we started to test them (all 5 at same time) and it both 4.16 and 4.17 crashed. Only 2 controllers + less or equal than 2 trackers set work without crash.

I have tried to disable most of plugins including some of enabled by default, but that didn’t help.

For the time being we had to switch to Unity, leaving initial UE4 project for a time when it won’t crash every time we start editor with all required trackers active.

Attaching last crash dump that should be related to the crash.

Thanks for reply, Rudy Q.

link text

No, I don’t use third party plugins and the issue exists in empty projects with defaults settings. Is Anry’s log enough? He’s definitly describing the same problem.


Hello YuriNK,

Could you test to see if you are still having this issue in the 4.18 preview build of the engine?

Yes, it still crashes on 4.18.0 Preview 2
link text

Probably this observations could help. Some time ago I figured out that sequence of enabling trackers is important. For example today UE crashed at start. I restarted SteamVR and turned on trackers in another sequence. After that UE launched successfully, but it crashed on any input from left motion controller, incluing simple touch (not press) at trackpad.

I’d say it’s a hardware issue, but SteamVR itself and non-UE applications works normally, so it’s at least not hardware-only problem.

I believe that it takes first 2 controller/tracker devices as motion controllers. And because Vive trackers does not have any buttons/triggers/trackpads as controllers, UE crashes when some code that check state/validity of these hits assert.

Yes, UE only supports input from normal motion controllers.

Just noticed that it goes on for a 3 months already :frowning:

Hello YuriNK

This issue has been reported. I have provided a link to the public tracker. Please feel free to use the link provided for future updates.

Link: Unreal Engine Issues and Bug Tracker (UE-54387)

Make it a great day

No, at least in the current Preview 4.

I’ve been trying to do a rebuild today all afternoon with the Unreal Engine Issues and Bug Tracker (UE-54387) fix and have over 200 errors… a lot pertaining that bit of code… is this a dated fix? am I doing something wrong? I’m following documentation on rebuilding the engine from source, and adding those 3 or so lines of code to the proper file with VS2017.