Invalid background properties (imageFit, imageTransparency, imagePosition).

A visual or page background uses image properties that aren't valid in the schema.

Why it happens

• imageFit, imageTransparency or imagePosition added to a background object where the schema doesn't allow them.
• Copied from an incompatible example.

How to fix it

1. Remove the invalid background properties from the JSON.
2. Set the background image through the Desktop UI instead.
3. Keep the background object to keys valid for your schema version.