How do I restore the default background image (for login scree and dashboard) after a NC upgrade?
I never changed the the default background image, because I was happy with the default (the image with a blue background, clouds at the bottom and the NC logo above the clouds).
The upgrade to NC 30.0.1 somehow messed with that background image. It was scaled at a ridiculously high factor such that the center part with the NC logo only was scaled to the entire screen and the image was completely blurry.
Hence, I went to “Admin Settings → Design” and removed the background image. However, now it is completely gone and the background is a simple plain blue. If I press the “revert” button to restore the default image, I am back at square one, i.e. the ridiculously scaled image is back.