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)
Dell SNPTP9W1C/16G 16 GB 2666MHz (PC4-2666) Memory Ram
$34.95
A-Tech 8GB DDR3 1600 PC3-12800 Laptop SODIMM 204-Pin Memory RAM PC3L DDR3L 1x 8G
$13.99
Team T-FORCE VULCAN Z 32GB (2 x 16GB) PC RAM DDR4 3200 (PC4 25600) Memory
$54.99
T-force Vulcan Z DDR4 4000 32gb (2x16)
$60.00
Crucial DDR3L 16GB 1600 2x 8GB PC3-12800 Laptop SODIMM Memory RAM PC3 16G DDR3
$22.45
HyperX FURY DDR3 8GB 16GB 32GB 1600 MHz PC3-12800 Desktop RAM Memory DIMM 240pin
$15.90
CORSAIR Vengeance RGB Pro 16GB (2 x 8GB) 288-Pin PC RAM DDR4 3600 (PC4 28800) In
$47.99
8GB PC3L-12800S 1600MHz SODIMM DDR3 RAM | Grade A
$12.00
Dell Memory SNPK7G24C/16G AB883074 16GB 1Rx8 DDR5 UDIMM 4800MHz RAM
$98.95
Lot of 50 Mixed Brands 4GB DDR3 DDR3L-1600 PC3L-12800U DIMM Desktop RAM Memory
$84.99