How does a canvas get created...if I didn't create it?
I was working on a scene last night and I noticed that at the bottom of the render settings panel just under environment, there was the word CANVAS. But it looked like it was grayed out.I clicked on it and there was a drop down with one item in it. I had seen references to canvases before and I figured that's how people got them. But I didn't know how to use them or what they were for and I wasn't going to take time to delve into it right then. Oddly, I don't remember seeing the world canvas there before at the bottom of the list. I went on and finished the render. I had a figure, some hair, some clothes, an environment set, some lights from DimensionTheory. When the render finished, only the left half of the render window closed. The right half was still there, (This was the window that shows the iterations.) I waited and hoped that it was going to go away becuase I ddidn't want DS to crash. Finally it did. Then I saved my image.As soon as the save window closed, DS crashed. When I checked my render library, the render was there, but not the small icon that also gets generated. Photoshop would not open the render image. But some windows programs would. I was able to save a copy that Photoshop could use.
So did the canvas have anything to do with all of this. Perhaps because it wasn't set up right. Like I said I never turned the canvas on. I read that you need to go to the advanced tab and check canvas. I never did that. But apparently I have created a few canvases over the years without knowing that I was doing it. (I see the files at the top of my render folder. I figured they were program files and just ignored them.But now I know they are canvas files)
Do some products create canvases when you load them?

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That happened to me, and on investigation I concluded it was the use of the HDRI set 'Rain City Chicago' that also when loaded, set the canvas options.
Thanks. I do have the product you mentioned. I was tempted to use it, but I elected another. It must have created the canvas. Now to learn what they are for and hwo to use them.
So I just bought that HDRI but haven't used it yet. Is there a problem wit the product that affects later renders after you use it once?