In the first example above:
/dev/mapper/luks-f25862ef-6be7-487f-80c0-aa21ce26319e: UUID="c4ccc1dc-6738-48a0-8922-afa3b7ee11fd" TYPE="ext4" #line 9

which is missing. The UUID & Luks-... do not match.

You are saying I should have always used the UUID vs. the luks-.... line in cryptab & fstab ?
How should the whole line look?

They won't match. The first contains the UUID of the LUKS container. The second is the UUID of the ext4 filesystem within that container. If those were the same it would violate the expected uniqueness of UUIDs.

That name in /dev/mapper can really be anything. It is determined by the first argument in the /etc/crypttab line, and the device name in the /etc/fstab entry needs to match. Using a name that contains the LUKS UUID is just a convention that the installer uses. Your line in /etc/crypttab could be as simple asand your /etc/fstab would then need an entry referencing "/dev/mapper/mystuff".

do I make a empty file in /dev/mapper/mystuff

or do I use:
UUID=31e49c7a-7071-4a36-a58d-9a35638e5235 none
or something else?


A current working fstab:

/dev/mapper/luks-f20124ef-6be7-487f-80c0-aa21ce21239e /home/BIGDRIVE ext4 defaults 0 2 #SDB

so all it needs to be is:

/dev/mapper/mystuff /home/BIGDRIVE ext4 defaults 0 2 #SDB

The node /dev/mapper/mystuff gets created when the LUKS container is unlocked. The line in /etc/crypttab would be "mystuff UUID=31e49c7a-7071-4a36-a58d-9a35638e5235 none", as I said before. Using "none" as the password causes a password prompt when booting. Perhaps you are doing something else. I'd have to see an /etc/crypttab line from one of your other systems (with any actual password redacted) to know.Yes, if that's how you set up /etc/crypttab. The name in /dev/mapper is completely arbitrary. It just needs to match what you use in /etc/crypttab.

thanks. I will try tomorrow, super busy with Christmas business right now.