Hodgepodge issue to annotate all the incidences found while testing (manual or automated), inspecting logs... that still haven't been investigated or are true mysteries needing some research.

Of course, 7.4 related only. Will be adding them here, in the description, numbered, for further discussion. Once under control, they will be moved to a proper issue and documented here.

A) line 255 of /backup/util/ui/backup_ui_setting.class.php throwing different, non-sense, errors. See https://pastebin.com/0Hg9bXdi . Requires investigation.

B)