I just tried a clean install of Blender on Trixie, fully patched as of
29th July, based on Trixie RC2, and a clean machine. On switching from
Eevee to Cycles, and trying to render, I got a message that Blender
wasn't built with denoise support (which is consistent with the current
issue), and it failed to render. Once I unticked denoise, in the render
settings (two places, although maybe only one was needed), it rendered
the image properly.
Unless and until the current wishlist item is implemented, I believe the
default should be with denoise off.
Unless there has been a change since yesterday, this will be
4.3.2+dfsg-2, and the amd64 build.
(I think this is a minor bug, rather than a wish list item, so I might
create a new report, for this.)
