Description of the need While working on https://github.com/backdrop/backdrop-issues/issues/3979 I realized that the updater throws exceptions at an early stage of the process, when there's nothing broken (yet).
This might be confusing for admins, especially Backdrop novices, because an exception usually means, something's broken really badly. And that's not the case at that early stage of updating (files got downloaded and extracted, the install itself is untouched).

Doesn't this look like this Backdrop install is broken? It isn't.
Proposed solution If nothing's actually broken, it might be better to abort the update and show a helpful message. Log detailed information, possibly with links to documentation. We also need to consider that updating happens in batches. The fact that one project fails, doesn't mean all of them fail. (But that needs some more recherche...)
Alternatives that have been considered Sticking with UpdaterExeptions.
Recent comments
Oh thanx ! I had an "old" text format that I had disabled. I re-enabled this format in the field body with the permissions and the field comes back for editing.
Problem of access to the body field with a simple post
See https://github.com/backdrop/backdrop-issues/issues/7148
Problem of access to the body field with a simple post
I used the theme gin for admin. Perhaps, it's the problem ? I have a color border when i selected the images and of course i used the "ctrl" key.
Small problem with multi import files images.