One initial burp and so far the migration of about five sites has gone fairly smoothly. The burp, fortunately, is with a little used placeholder site with limited traffic. For whatever reason, the update caused issues or conflicted with the “classic editor” plugin and resulted in some content having some errors. Ironically, that site was the one where I had been experimenting with the new Gutenberg text editor plugin and had several pages/posts created using the new “block” editor. Apparently, WP5.0 didn’t like what the plugin had done. Oh well.
We will let customers know when the migrations are complete.