I've started getting a resolution not supported on my roku also. It will work fine with hulu and then I try to switch to Netflix and it shuts done with that message. It will also cut out sometimes. It looks like flashes of color or no sound. I would think it was my tv but it only happens when using the roku
What model Roku do you have? The older devices are beginning to become unsupported, and channel support isn't available any longer.
I’m also seeing the issue this last week with Netflix. Hulu, Amazon, and HBO appear to be fine but when I switch to Netflix I get Mode Not Supported screen. I have to unplug and plug in the Roku to get the Roku and Netflix to work. This is happening on two TVs both Samsung each with a Roku Ultra that are a couple years old. Everything worked fine until about a week and a half ago.