Yesterday a new version of Magisk became available on the Beta Channel (21.0).
As with the Gemini the direct update method will fail, but fortunately the custom os installer on the sd card from planet gives us a method to upgrade on the device.
I had success with the following steps yesterday:
1.) I started termux and got root with tsu. Obviously this requires that you are booted into rooted android. Then I checked the partition table with gdisk -l /dev/block/mmcblkp0 and noted that the boot partition is number 30. I think this is identical if you partioned in the custom os installer. So the command to dump the unrooted boot partition is:
dd if= /dev/block/mmcblk0p30 of=boot-original.img
2.) Start magisk, Tap on "Install" for the new magisk version, and under "method" choose "patch file".
3.) Create a backup of the rooted boot image from planet, if something fails you can use that to restore the old version.
4.) copy the magisk-patched.img file to the original filename of the rooted boot image from planet. The filename is "root-boot.img".
5.) Boot to recovery and launch the custom os installer then install "rooted android" to the correct partition.
After the next reboot to the rooted android you should see the updated version in magisk manager. (I would post a screenshot, but attachments are disabled at the moment.)
Have fun!
