Hey Folks,
this Problem drives me crazy. I have on several corners this (picture) dark ripped shadows. I have no idea where they comming from. The UVs are straight aligned and the mesh is a simple plane with holes for the door.
I hope you know something about this problem and know how to fix it.
https://thumb.ibb.co/hpZjSc/Dark_corners_2.png
https://thumb.ibb.co/d51W7c/Dark_corners.png
https://thumb.ibb.co/dVi00x/Light_Worldsettings.png
Try unchecking Ambient Occlusion.
Without AO it’s stronger/darker. Is changing nothing… 
Hi!
Did you say planes? You won’t get correct lighting with one sided walls…
Also your setting are “forced”! …indirect lighting intensity set higher… I’d say never a good idea!
Also turn off lightmap comression!
…one of your walls doesn’t have lightmap coverage at all…
The corners of your walls/ceiling are overlapping, which means that the shadow underneath will not line up with where the wall is, you need the corners to line up exactly.
em… lightmap resolution?
Hello and thank you for your Awnsers!
The walls are two sided planes.
I already put sown the indirect lighting intensity. But did not changed anything.
The edges of the roof and the ceiling are matching exactly. I’ve checked it in 3dsmax.
is set to 1024 (on the root mesh ofc)
Do you have portals in your openings (window, door)?
And just to make it clear: does your wall have thickness?
Yes the walls got thickness.
Yes Portals on every light entrance like windows.
How many lights do you have in your scene?
Are they intersect with your walls?
Could you turn off all the “fancy” settings on your lights and do a medium bake like that to see if it’s better?
Thank you for the answer. Can you please tell me, what you do mean by “fancy”? 
In this area are 6 spotlights. All together 43 Spotlights, 1 sun. Every with different attention radius (tablelamps etc.). Everyone on static. No one is intersecting with any object.
Sorry! :S What I meant is… what I would do to eliminate the problem is to reduce the whole lighting into minimal and build it up from that… So what I would do is keep just your main lights (skylight + directional if possible ans set 0 intensity meanwhile to the rest) reset all the unnecessarily (“fancy”! ;)) settings on these main lights (such as light angles and indirect light intensity…) and see the result… with 43 (or 6) lights + it’s more difficult to trace what causes the issue… IMO!!
