desktop background stuck on blue

Wondering if this Apple support article (link below) cam help:

How to: Customise the desktop picture on your Mac – Apple Support

or, whether you need to troubleshoot:

What to do: If your Mac starts up to a blank screen - Apple Support

"desktop background stuck on blue: my background changed and is no longer updating to a customized backdrop, any clues?"

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Troubleshooting a Blue Screen:

Getting this repaired might not be necessary. Try troubleshooting this using the following link.

Start Here: If your Mac Displays a Blue Screen at Startup - Apple Support