No preview image showing up when I plug the Viewer node in. I read elsewhere that I needed to render the image first. That worked for a little while but now it doesn't work anymore.


2 Answers 2


Just toggle one of your nodes off and on again.
Viewer/Composite nodes refresh only when there's a change in the compositor.

You can use M on your keyboard to Mute/Unmute a node.
Or just disconnect and reconnect it.

enter image description here

  • 1
    $\begingroup$ Thank you very much! $\endgroup$ Jan 18, 2020 at 4:47

For future readers (like myself), also make sure you have actually rendered your layer(s) first. The compositor does not render them for you.

You will know you have a rendered layer when you see the thumbnail of the “Render Layers” node, just as you see in jachym michal’s answer.


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