If the importing demo content failed and it showed the message bellow

Failed to insert row from line 2323 into table _fwbk_wp_options.
Duplicate entry 'theme_mods_topseo' for key 'option_name'


it's a bug in the latest version of Backup extension (2.0.16). Currently, you need to downgrade the version to 2.0.15 by following my instruction here.

  1. Go to the dashboard -> Plugins, deactivate and delete Unyson plugin 
  2. Download unyson.zip version 2.0.15 in the attachment file 
  3. Go to dashboard -> Plugins -> Add, upload unyson.zip here and acitve the Unyson plugin
Now you can run the Importing demo content again by going , it should work.