Here are some additional informations about the problem. I rechecked it was not a keyboard layout problem by setting up an additional luks key, a very short one that used only keys that were at the same position in both qwerty and azerty. It does not work, so it's definitely not a keyboard problem.
The error I get on boot is as follows: Caching passphrase for sdb1_crypt:*********************** [ 15.212421] device-mapper: table: 253:0: crypt: Error allocating crypto tfm device-mapper: reload ioctl on failed: No such file or directory cryptsetup: ERROR: sdb1_crypt: cryptsetup failed, bad password or options? Caching passphrase for sdb1_crypt: I tried to use a key file instead of a key typed by user just like I did on the other laptop. I do not want to use this method for this specific machine for security reasons (it should not be abel to boot unattended), but tried it temporarily. I regenerated the initramfs after changing the /etc/crypttab file, but it didn't work either. When generating initramfs, I got the following warning, so it may explain why it didn't work. cryptsetup: WARNING: Skipping root target sdb1_crypt: uses a key file In this case (booting with a key file), the error was different: Volume group "vg-ssd" not found Cannot process volume group vg-ssd Volume group "vg-hdd" not found Cannot process volume group vg-hdd Volume group "vg-hdd" not found Cannot process volume group vg-hdd Volume group "vg-hdd" not found ... Cannot process volume group vg-hdd Volume group "vg-hdd" not found Cannot process volume group vg-hdd mdadm: error opening /dev/md?*: No such file or directory Cannot process volume group vg-hdd Volume group "vg-hdd" not found then the boot process drops to initramfs shell. Exploring the filesystem at this stage, I didn't find the key file. best regards, Luc