Vray Light — Gen Not Working

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 restarted 3ds Max. Reset the scene. Tried "Morning." Same thing. The dome light stayed stubbornly black.

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.

The little progress bar appeared... crawled to 100%... and then… nothing. The Light Gen window went blank. The dome light in the viewport was still dark. No textures. No preview. Just silence. vray light gen not working

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

That was it.

Alex thought, "No problem. I'll use V-Ray Light Gen. Click a preset. Done." This is a frustrating moment for any 3D artist

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.

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

Alex’s Windows username was — with a space. Reset the scene

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

Panic.

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."