How do I troubleshoot some unexpected error messages reported while booting Debian 10?
Remove some files with
sudo rm /sys/fs/pstore/dmesg-efi-*.enc.z
This has been reported before. See e.g.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902966;msg=10
. Others simply mention sudo rm /sys/fs/pstore/*, I am not certain it is needed.
At any rate, it seems that, if your system is working fine, you may get rid of the information in pstore.
More about the persistent store pstore:
https://utcc.utoronto.ca/~cks/space/blog/linux/PstoreAndACPIERST. Pstore is a kernel feature that dates to 2011. It provides a generic interface to storage that persists across reboots and gets used to save kernel messages during a crash, as covered in LWN's Persistent storage for a kernel's "dying breath" and the kernel documentation. Your kernel very likely has pstore built in and your Linux probably mounts the pstore filesystem at /sys/fs/pstore.
https://lwn.net/Articles/421297/
pstore: new filesystem interface to platform persistent storage Email between Tony Luck and Linus Torvalds.