Render Patches

[SallyM]

Hi,

Pretty new user here -
I have been rendering the same file throughout the day with no issues but then suddenly the render file has developed patches which refuse to render to the same quality as the rest. I have tried restarting the software and even creating a new file from scratch but I have the same problem each time.
The render starts as a black screen and when it comes back there are parts of the model / background which never smooth out.
I have attached an image taken at the start of a render. Any ideas?

Thanks,
Sally

[SebastianG]

I had a similar issue and I increased the shadow quality from 1 to 3 and it got better.
You can find the shadow quality in the "Lighting" Tab.