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.
GitHub Issue #:
3577
Recent comments
Hello @NumerousHats, I agree with your assessment. I am looking into this situation right now. The root of this problem is that Backdrop CMS is implemented on top of a "stack" of...
Update Core and Theme via Web interface
I just installed a Backdrop CMS site with version 1.27.0. I then used the user interface to download and update Backdrop CMS to 1.30.0. After starting the update process, and on the...
1.30.0 update.php generates incorrect link
I believe my permissions are set up correctly, as I can install modules from the UI. But for whatever reason, I can't update them. I will, however, double check against that documentation.
Update Core and Theme via Web interface