If you do - get the latest testing ISO - a stable update is planned to next week - but installing the usb_modeswitch package will likely get you back on track.
I got triggered by the offline part as I realize that a large part of any userbase may have connectivity issues.
If you have the means and the opportunity there is a method which may work well for you.
The method was a result of topic created by another member on doing an offline update and possilby installing new packages Updating an Offline Manjaro Installation.
Techically - instead of using an online mirror - you use a portable mirror. There is a bandwidth overhead when syncing - but the advantage is that your portable mirror will always reflect your system state - thus you can install any package you like - offline.
- acquire a portable storage of 128G
- technically it can be a partition on your system but removable is better as it can be used to update other systems as well
- connect to a network with a stable internet connection
The result was this rsync
#!/bin/sh
#######################################################
####
#### Variables to amend
####
TARGET="/path/to/portable/mirror"
TMP="/tmp/manjaro"
LOCK="/tmp/rsync-manjaro.lock"
SOURCE="rsync://ftp.halifax.rwth-aachen.de/manjaro/"
[ ! -d "${TARGET}" ] && mkdir -p "${TARGET}"
[ ! -d "${TMP}" ] && mkdir -p "${TMP}"
exec 9>"${LOCK}"
flock -n 9 || exit
if ! stty &>/dev/null; then
QUIET="-q"
fi
##################################################
###
### This rsync command creates a copy of stable repo
### where symlinks are converted to regular files
### Expect the size to be around 50GB to 80GB
###
##################################################
rsync -rtLv --safe-links \
--delete-after --progress \
-h ${QUIET} --timeout=600 --contimeout=300 -p -c \
--delay-updates --no-motd \
--exclude="arm*" \
--exclude="pool" \
--exclude="testing" \
--exclude="unstable" \
--exclude="stable/kde-unstable" \
--temp-dir="${TMP}" \
${SOURCE} \
"${TARGET}"
rm -f ${LOCK}
And and accompanying script for setting up a local webserver to serve the mirror
#!/usr/bin/env bash
## sample script for updating a remote system with no network
## using a labeled filesystem on a portable medium
## mount using label e.g. ManjaroRepo
sudo mount /dev/disk/by-label/ManjaroRepo /mnt
## start the python http server
python -m http.server -d /mnt 8080 &
## use pacman-mirrors to point pacman to the local mirror
sudo pacman-mirrors -aU http://localhost:8080
## update the system
sudo pacman -Syyu
## optionally reboot the system
#reboot
If you - instead of syncing your system to an online mirror - sync your offline mirror on the portable medium - then sync your system with the portable mirror.