When I boot from knoppix with no compact flash in /dev/hdc, I have no error messages. When I boot with the compact flash in /dev/hdc I get an error as follows:
Uncompressing Linux... Ok, Booting from the Kernel
Ide-scsi: hda: Unsupported command in request queue (0)
pdcraid: Error reading superblock
Ide-scsi: hda: Unsupported command in request queue (0)
pdcraid: Error reading superblock
Ide-scsi: hda: Unsupported command in request queue (0)
silraid: Error reading superblock
Then it loads knoppix-autoconfig with no problems, and I can even mount /dev/hdc with no problems and read/write to it. The system functions normally.
I cannot have the visuals of errors on the screen though, as this is for an installer CD.
I think it may display that message three times because I have three partitions on hdc (hdc1, hdc2 and hdc3).
Let me know if you have any ideas about this...

WAVLINK RAID 2 Bay Hard Drive Docking Station SATA 2.5/3.5'' SSD HDD Enclosure
$107.99
Broadcom 9600-24i Tri-Mode RAID Controller 4.0 NVMe SAS SATA NEW 05-50111-01003
$639.69
G-Technology G-SPEED Studio XL 48TB Thunderbolt 2 Storage
$200.00
Intel VROC Premium RAID Controller Card PCIe Add-On Module VROCPREMMOD
$265.00
Lot Mini SAS SFF-8643 To 4 SATA 7pin Hard Disk 6Gbps Data Server Raid Cable 1M
$870.00
Broadcom LSI 9305-16i 12Gbps SAS-3 PCIe x8 HBA 16-Ports Raid Controller
$64.99
2-Bay/4-Bay Hard Drive Enclosure for 3.5"/2.5'' SATA HDD/SSD 10Gbps USB-C 3.2
$75.99
Oyen Digital MOBIUS 5-Bay RAID Enclosure USB 3.0/eSATA/FireWire
$130.00
Lacie 2big Quadra RAID 2 x 2 TB 4 TB Only 158 hours
$199.00
Vintage Promise EIDEMAX Enhanced IDE Disk Controller ISA Non-RAID Card Boxed
$34.99