I couldn’t do a ‘sudo apt-get update’ on my Pi 3 running Raspbian as I got this error:
Fetched 74.9 kB in 31s (2,381 B/s) Reading package lists... Done
W: GPG error: http://security.debian.org jessie/updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9D6D8F6BC857C906 NO_PUBKEY AA8E81B4331F7F50
To import the missing keys:
sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-key AA8E81B4331F7F50
sudo apt-key adv –keyserver keyserver.ubuntu.com –recv-key 9D6D8F6BC857C906
Tips from here.
What not to do: reset your password before you change/setup your keyboard locale, use punctuation characters in your new password, and then change the locale. Yeah, that’s not going to work. Now I don’t know where some of the characters moved to 🙂
I’m going to leave this post right here for future reference.
Update 2/3/16: after I edit the cmdline.txt and booted to a shell, passwd gave me this error:
passwd: Authentication token manipulation error
passwd: password unchanged
Further down the post, this recommendation to remount / solved my issue:
mount -rw -o remount /
Then I did passwd and the change worked this time.