@Cor-Slagmolen what PI is this on?

edit ~/MagicMirror/package.json

change this line

"start": "DISPLAY=\"${DISPLAY:=:0}\" ./node_modules/.bin/electron js/electron.js",

to this

"start": "DISPLAY=\"${DISPLAY:=:0}\" ./node_modules/.bin/electron --disable-gpu js/electron.js",