Unreal 5.3.2 on MacOS 12.6
My project crashed when I was dragging a mesh from the content browser.
On restarting all colour and lighting is lost. The landscape is flat white, while the sky and static meshes are flat black. I’m using Ultra Dynamic Sky, which appears as normal for maybe a second and then fades to black.
I’ve tried restarting but the problem persists.
I’m a bit of a beginner and any ideas of where to look to fix it would be appreciated.
Hey @hostprods! Welcome to the forums!
It might be easier to figure out what’s going on with more information!
Things like:
What did you do in your recent “workday” when it crashed?
Anything lighting related is important here!
Can we get screenshots?
Get that stuff together and we’ll be way more likely to be able to help! 
HI, of course…
I was so over keen to post that I forgot to add all that stuff.
As mentioned, for lighting I’km using Ultra Dynamic Sky - which has never caused me a problem in other projects. There is no additional lighting.
At the time of the crash I had recently painted some foliage and then gone to Quixel Bridge to get some rocks. It was when I was attempting to drag the static mesh of one of these rocks from the content browser into the level that the crash happened.
On reopening the project appears as you see it in the attached image. I have rebuilt everything twice but with no joy.
adding as well the message log from the lighting rebuild, in the hope it sheds some light on it. (no pun intended, but happily accepted…)
Okay, so it seems like maybe after you added all of that “InstancedFoliageActor_0” It tried to compute the lights when you added in the rock to the content browser… try clicking the name of it next to the magnifying glass, it should select the foliage actor (one of them) and it will tell you what’s causing the issue. It might be too many lightmaps too close together.
I suspected that as well. The message log wasn’t saved so I couldn’t investigate what you suggested. So I just deleted all the foliage (I wasn’t all that attached to it anyway) thinking that that would remove any lighting conflicts.
No joy
I deleted and readded Ultra Dynamic Sky and rebuilt everything to see if that would refresh it but also no joy.
The project is only a about 3 hours of work so far, and I can easily delete and start again. I’d still like to try and find out what has happened though, if possible.
Unfortunately, I can’t find anything that doesn’t say “Corruption.” 
This is just one of those occasions that teach. Always make backups!
Personally I have an external HDD that I keep the long-time backups, and a usb drive that keeps my most recent 3 sessions for each project, updating. There are multiple ways to go about it but the point is backups aren’t nice, they’re necessary- as much as I hate to say it. I’ve lost big projects before myself.
