Indeed to the average user this appear quite a crisis, that s/he canot understand save coming here. Any hint that the decryption issue "may come from a different algorithm used on the note originator machine' or something like this would be welcome. (is there already an option to automatically check 'we are on the latest version'?)
Agree with this, and we're taking steps to improve these error messages. Ideally we'll also make sure we do encryption upgrades in such a way that there won't be any error.