Quickly creating an issue for this; proper issue summary will follow.
https://www.drupal.org/docs/8/upgrade/upgrade-using-web-browser#pre-upgr...
If the database credentials to your source database are correct, the upgrade review page will appear as illustrated in the screenshot below. This page shows a summary of the upgrade status for all installed modules on the old site.
Latest iterations use this help text instead:
The new site is missing modules corresponding to the old site's modules. Unless they are installed prior to the upgrade, configuration and/or content needed by them will not be available on your new site. Read the checklist to help decide what to do.

Recent comments
I missed this topic: Self-Hosted, Headless, and Hyper-Automated: The Backyard DevOps Stack for Backdrop Applications (Part 2) from November 8th. Is there a way to watch it somewhere?
Backdrop Live November 2025
I'm not sure I'm getting it. It is working as intended now. Let me post you some images. Thanks!
have a view show contents in table and leaflet format simultaneously.
https://github.com/backdrop/backdrop-issues/issues/7018 Feel free to edit as you see fit. KR Mike
MySQL Database 4-byte UTF-8 support