VR Mirror Window turned Black

I’ve been working on a Project today, pretty far in.

When I discovered a Method to display only one Eye undistorted to the HMD Mirror Window.

I added the Execute Command “HMD mirror mode 2” and “Fullscreen” to my Levelblueprint.

Now the Screen of the Mirror Window is black at all times, the View in the HMD (HTC Vive) is still fine.

Any ideas how I solve this problem? Reverting the Settings to default and Changing HMD mirror mode to 0 again did change nothing at all.

For the time being, I have to use the Headset Mirror of Steam VR which works fine, but it is very inconvenient to develop this way.



Strangely this even happens on a different Map on the same Project. Haven’t tried another Project yet.
Maybe there’s some issue with the Hardware, we’re using a 970 for the PC I am working on.

I had the exact same issue. Evidently, those console commands were written for Oculus VR rather than Vive. Not only do they not do anything, but they also turn the screen black.

To fix this, I migrated the map in question to a new UE4 project entirely. Every other UE4 project is unaffected. Perhaps there is some way to reset or wipe console commands that had been used, but I’m unaware of how to do that.

EDIT: Also, are you able to open the project on a separate PC?

Thanks for letting me know!

I will try the method you provided.
I hope there’s also another fix for this, since It seems like something that you should not have to do.

I’ve just hit this same bug. Now the VR preview window is completely black and I can’t get the preview back :frowning:

OK, thought I would report in and let you know how to fix this if you don’t fancy migrating your project :slight_smile:

Close project.

Go to your project folder -> Saved -> Config -> Windows -> Engine.ini



So the 0 is either 1 or 2. 1 for a mono view, 2 for stereo view.

Hopefully this will save you and future people some time until this is fixed.

If anyone can work out how to change the size now on HTC Vives, that would be great!

Thanks UKdude! I’ll definitely need this in the future when I go back to that project.

Solution is do delete the following folder


Delete it and it will work properly again.

I ran into this myself, and this has been logged as UE-32419 , Even if it isn’t supported you shouldn’t have be stuck in a “broken” state. So it should simply not do anything if it isn’t supported :slight_smile:

Thanks for fix Osok!

Terminal still work if screen is black, you just have to type carefully. “HMD mirror 2”, not “HMD mirror mode 2”

Until you package it. (4.13)

If you type in “HMD mirror 1”, you should get your window restored from the black screen. You can also bind keyboard commands to execute the console commands, so you can switch between window viewport modes even if you can’t see the screen or open up a console window.