WP white screen of death after duping a site that works fine on same server

FYI, I resolved the problem by installing a fresh copy of WP and re-using old database. WP updated my database. I then copied the theme and enabled it. Finally, I manually installed all the plugins (automatically updating them) and that was it.

In future, I recommend getting the latest WP when you have an opportunity to dupe your site. You get latest versions of everything and it’s easier to debug the site when you don’t have a white screen of death as the starting point.