Update: I tried manually updating the theme on my test WP site and had the same browser crash occur at the same point: as I scrolled through the list of files using the manual Dashboard->Themes->Install Themes->Upload->Choose File routine. So the problem does not appear to be with this plugin but more generic in my WP installation. To test “uploads” in general, I successfully uploaded some new items to the Media library
I’m baffled and would appreciate any input about what might be going on and how to fix it.
Thanks, Bill