Error when I'm starting a track

My footage is 2609 frames long. I’m trying to track a brick wall where the performer pass through it (there is a hole in that wall).
I’ve made a first layer of the performer himself.
Then I made a second layer for the wall.
The blend mode of the performer layer is set to subtract (in order to track the wall behind him)
When I start the track of the wall layer, few seconds later I’ve this pop up message every time:
“GPU Tracking error. Calculation error. Please send an error log to support.”
I’m using After Effect CC 2018. Same problem with AE CC 2017, even with the GPU track disable.
With a little bit of search, I didn’t find any similar topic with this error …

Windows 10
Core i5
GTX 1060 Ti
16 Go RAM

Hi there!

You don’t need to set the matte to “subtract”. Any layer in the foreground will automatically occlude the background. You only need to set a blend mode if you’re rendering or exporting mattes.

When you attepmted to turn off GPU tracking, did you restart After Effects? The host needs to be reset in order to update the preference.

Having said that, most Nvidia cars on Windows should work. What current graphics driver are you using?

I just restart AE as you said and change the blend mode back to “add”, seems to work !
Thanks for you help.
So when you want to track something behind someone the correct path to take is a layer for the foreground then a layer for the object we want to track and that’s it ?
I’m a beginner with Mocha and I just use it for tracking. Do you know good ressources to learn all the features of Mocha ?

Finally work ! Thanks again

We have the fundamentals of mocha available online for free here: Boris FX | Videos

Start at lesson one and continue through to the end and you will have a much better grasp of how mocha works, planar tracking, layer order, and more. All you have to do to hold one layer out from another is put it above the layer you need it to hold out from, it’s a user defined workflow that puts everything closest to camera at the top of the layer pile and everything further from camera below those layers in order. If you track from FG objects to BG objects you’ll always have holdout mattes for your tracks.

Cheers,
Mary