Why did the FCS client fail to verify the Vendor Authorized Boot (VAB) file?

Description

You might see this error when performing a VAB file verification via fcs_client (e.g., signed-bl31.bin , u-boot.itb, kernel.itb).

command for read out session ID:

./fcs_client -e

command for perform verification :

./fcs_client –V <bitstream.vab> -s <sessionID>  --loglevel=4

Error message display, when verified signed-bl31.bin:
root@agilex7dksiagf014eb:~# ./fcs_client -V signed-bl31.bin -s 869f2929-c2d3-b64a-bbc7-c003718d60ed --loglevel=4  
[ 2831.587900] Session UUID Mismatch ret: -22
[ 2831.592065] Failed to initialize digest ret: -22
[ 2831.596698] Failed to perform get digest update
[err:]Failed to write to sysfs attribute
[err:]Error in getting digest
[err:]Error in calculating image hash
[err:]Error in verifying image hash noffset=0

Error message display, when verified u-boot.itb/kernel.itb:

root@agilex7dksiagf014eb:~# ./fcs_client -V u-boot.itb-s 869f2929-c2d3-b64a-bbc7-c003718d60ed --loglevel=4   

[err:]Error in getting image data noffset =