Failed executing external process for 'light transport' job. Error baking with precomp GI

Having this issue now and then, still don't get what it may cause it.

I have a decently sized scene; 275K tris, so nothing too inhumanly big. My rig is an i5 4690k with 16 Gb of ram and GTX 970; decent machine, works just fine for 99% of my games and applications.

At times, especially when I need to rebuild the cache for a project; and have to bake lighting, I get these error messages as in the title.

There is virtually nothing else in the log window, beside the error itself. I bake with realtime GI only; got 1 omnidirectional light, 8 spotlight and some light probes for the interior part of the scene.

I would like to know why these error happens, and why it takes hours to get the baking done...at the moment it is stuck at 7/11 light transport | 52 jobs, and I see already 4 of these errors.

Can someone clarify why are these errors happening, and why it takes so long to get GI calculated? Most of the times, the light calculation takes not longer than a minute or 2, but when these errors happen, it seems like the baking takes 20x longer.

BTW this is happening with both Unity 5.3 and 5.4 beta (both 64 bit).

 

I am having the same issue... Any updates?

 

Mine also seems to hang or crash during "7/11 Light Transport". Seems to take hours and i don't know why... this same bake used to take 20 minutes...

 

You need around 100 GB HDD drive for GI Cache. also after i upgrading to 5.4.1 ,my problems solved.
Also you can download 5.4.2 and use it without any issues .
Sometimes also you need reinstalling windows to solving this problem.

 

I test a scene with exactly same settings. unity 5 takes 34 min and unity 4 takes 4 min.

In unity 5 ,first you can bake your scene with very-low preset and low resolution, then bake your scene with higher preset .

Lowest settings for bake fast and good results for mobile target:

 

i already have 5.4.2 and Cache size makes no difference.. Unity just crashes every time i bake..

 

100GB？！！！Wow that's so terrible...Actually did Unity really used for 100GB?!

 

Not really 100gb. You can bake with 10 gb.I'll use this for large environments.

 

You don't *need* 100gb, but if you are working on quite a few scenes at a time and you want to keep the cache for each of them so subsequent bakes are faster, 100gb sounds about right.