This is probably caused by running out of memory. This could happen because of many reasons, and some of them include:
- Using displacement with high-quality settings in a high-resolution image (e.g. displacement screen size lower than the default 2 px, in a scene rendered in resolution higher than 1920 x 1080 px).
- Rendering large numbers of objects or detailed meshes (a "heavy" scene).
- Using many render elements (especially LightMix) within a high-resolution rendering.
For possible solutions, see: I am getting a sudden rise in RAM usage!
If the problem is caused by something else (for example, it disappears after deleting some object or material), please report it through our Support Portal.