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."
They restarted 3ds Max. Reset the scene. Tried "Morning." Same thing. The dome light stayed stubbornly black.
It was 2 AM. Alex had a villa exterior due in 12 hours. The client wanted "dramatic, cinematic sunset lighting."
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.
That was it.
Alex’s Windows username was — with a space.
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.
Panic.