Comment 0 for bug 1254447

Following the normal procedure to upgrade with the update manager doesn't work. No error message, just stops working.
Starting it from the command line: sudo update-manager -d
Produces a stack trace in the terminal. The error is: UnicodeDecodeError: 'utf8' codec can't decode byte ...
This is in function _add_file_to_tar_with_password_check
(Sorry, didn't copy the whole stack trace; however you should be able to reproduce it from the instructions below).

The cause was a hidden file in /etc/apt/sources.list.d
This is a Vim undo file, which has a binary format, thus not utf-8 encoded: .google-chrome.list.un~

1. First of all, if the updater crashes with a stack trace, a dialog should appear to report the error.
    Pointing to the log file, which I later found out to be /var/log/dist-upgrade/main.log, would be helpful.
   I waited several minutes, thinking that it was busy in the background.

2. The update must ignore hidden files. The user may edit files with Vim, which may leave hidden undo files behind.
    A better solution is to only use files that are known to be relevant, not blindly processing every random file.

3. If the update fails to read a file there should be an option to ignore the error and continue. Listing the file name and/or contents should give the user a hint about what he is skipping. This is the only way the upgrade can continue from a damaged system without the user manually hunting around for problems and guessing how to fix them.