Vray | Light Gen Not Working

They selected the dome, chose "Sunset," and hit .

That was it.

This is a frustrating moment for any 3D artist. Let me tell you a short, relatable story about this exact problem, then give you the most likely fix.

They Googled furiously: "vray light gen not working" — and found forum threads from 2018, vague mentions of "paths," and a buried comment about "Windows usernames with spaces." vray light gen not working

Alex thought, "No problem. I'll use V-Ray Light Gen. Click a preset. Done."

It was 2 AM. Alex had a villa exterior due in 12 hours. The client wanted "dramatic, cinematic sunset lighting."

Alex’s Windows username was — with a space. They selected the dome, chose "Sunset," and hit

Twenty minutes later, after sweating through the fix, Alex had a beautiful golden sunset. They delivered on time. But they never forgot: check the damn path spaces.

Panic.

They restarted 3ds Max. Reset the scene. Tried "Morning." Same thing. The dome light stayed stubbornly black. Let me tell you a short, relatable story

The fix? Change the to a simple path like C:\VRayTemp (no spaces). Or, in newer versions, update to the latest hotfix.

V-Ray Light Gen, in some versions, fails to write temporary HDRI preview files to a path containing a space. It silently fails. No error. Just a dead, dark dome.