Originally Posted by
_defalt
@g3ntl3m3n Most of the components of kali live are read only and not writable so they can't be updated unless you create a persistent partition to save new data. But even persistence doesn't upgrade kernel version.
While the error you are getting is not associated with your storage, it has something to do with writing data on read only components.
The better option is to install kali on your 256GB USB. Kali installation requires atleast 25GB partition including swap partition. You can create more partitions for local drives.