See: https://github.com/fedora-iot/greenboot/issues/93
The 01_update_platforms_check script is failing because the loop over the UPDATE_PLATFORM_URLS variable is treating the list of URLs as a single value.
The URLs need to be split and checked individually.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (greenboot bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2023:2438