I try to decrypt my harddrive using the password that I 100% know. The password knowledge is not the problem.
Last thing I remember doing is: installing texlive. Not having enough disk space. Removing texlive again. followed by
apt update apt upgrade apt dist-upgrade
I remember the update had an error due to missing internet connection (wifi switch was off) After I switched on wifi, update, upgrade and dist-upgrade went (I don't remember otherwise) smoothly.
Starting my machine this morning brings me to the current state of affairs:
No key available with this passphrase cryptsetup failed. bad password or option?
The password contains special characters - can I somehow test which symbols are created by a keypress? Maybe the keyboard layout switched or somithing similar.
This problem is on Debian Jessie. Except for header backups, what else can help me investigate?