I got the bug for the first time last night. V3, t-pose, some morphs for body and face, V3 tunic and pants, default lighting, and nothing else in the scene (not even a background color change). I worked for hours just fine, and got the error when trying a high-res render.

High res renders had worked on the same file yesterday so it's likely some combination of:

1. A memory leak and it happened because I worked with the same file for four hours; or

2. Swapping large textures in and out a lot, because that's what I was doing for the four hours (creating a new clothes set for the tunic and pants).