This message occurring during boot up of KNOPPIX-Live has no deleterious consequences but it is an annoyance.
It is probably an unintended hangover from the HD-installed version which allocates several partitions.
Either ignore it or include a (2nd and) 3rd (and 4th) partition in your boot device, even if it is a USB stick.
Use fdisk* to set /dev/{sda}1 as the KNOPPIX partition type c (being FAT32; or NTFS if you prefer - I've never tried this).
Set /dev/{sda}3 as type 83 (Linux) (at least 400M). Then format it as Reiserfs with mkreiserfs .
It's not obvious to me how (or even whether) the partition is used; but it is made available; and you will boot
without the annoying error message!
(*) Yes: you need to format your intended USB device - from a temporary KNOPPIX USB device is probably your most
convenient method ;o)
Extron RGB-160XI Analog Computer Video 60-378-01
$187.06
Analog Computing The Magazine Atari Computer Owners February 1984 No. 16
$12.00
NEW Aquarius+ Computer Signature Edition - 8Bit Retro System
$209.00
$18.00
Apple II V2 ANALOG VGA & Z80 PCPI Applicard Softcard PicoPal IIe Ralle version
$69.00
TRS80 Color Computer 1/2/3 Dragon 32/64 Atari Joystick Adapter
$25.49
CH Products MACH III Analog Joystick Beige Orange Black.** Untested **
$49.99
Apple II V2 ANALOG VGA & Z80 PCPI Applicard Softcard PicoPal IIe as seen online
$69.99
Apple 661-0287 5.25" Unidisk Analog CD Card Vintage 1986 820-0190-A
$154.00
2004 Honda Civic Engine Computer ECM ECU 37820-PLR-A72 OEM (AA 108)
$88.99