Hello Rikard,
Here are the instructions. We followed them, but the same error keeps occurring.
How to manually import a theme demo
•
• Please add following line to Functions.php file in Appearance > Editor
add_theme_support( ‘avia_demo_store_downloaded_files’ );
• Download the zip file of the demo you would like to import from https://github.com/KriesiMedia/enfold-library/tree/master/demos
• Extract it in \uploads\avia_demo_files\ folder. If you are importing Enfold 2017 demo, files should be extracted inside \enfold-2017\ so it should look as \uploads\avia_demo_files\enfold-2017\
• Go to Enfold theme options > Demo Import and import the demo