Buffer I/O error after upgrade

[durzino]

Hi all,

I have Ubuntu installed on an external device, because the internal device had error, likely it is broken.
After an update , at boot my monitor shows:

"Buffer I/O error on /dev/sdb"

So I skip in a recovery shell.
Ubuntu is installed on /dev/sdg that is my external disk.

Why Ubuntu looks for /dev/sdb?

Thanks

Best Regards