That's what you get for using "@" muting informative errors.

Use internal classes to restore a backup, to prevent overwrite by our singleton object

The GUI upgrade still has serious problems coping with the
fact that it is being updated.  In the latest upgrade the
move of set_language() causes an error so we just avoid it
and do the work again when we can.

last bits and pieces for https://github.com/opnsense/core/issues/117 although rc.filter_synchronize really needs a rewrite at a later moment.

Has it really been this way forever?  While there, chain
mwexec_bg() throgh mwexec() to avoid duplicated code and
increase error reporting.

daemon(8) will completely detach and keep running so maybe that
will be one step closer to reliable firmware upgrades.