encrypted root not boot'n with 5.7.1 (1 reply)

i set up my nsa320 in 2013 with an encrypted root on the hard drives use'n kernel 3.4.4 and debian wheezy. it has served well for many years. i thought i would bring it up to date so i upgraded to stretch. still use'n the 3.4.4 kernel everything works ok. i thought i would push my luck and upgrade the kernel. i followed the instructions at

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https://forum.doozan.com/read.php?2,12096

for the 5.7.1 kernel. the ramdisk runs ok and it finds all of the disk devices but never prompts for a password to decrypt the devices. it returns

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Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

i have tried too many options to list and none help.