I followed the process to auto update my install today and got a nasty exception thrown.
A refresh seemed to go through OK, but def. something to look into.
This looks like an incomplete update.
If your tmp/latest folder contains a piwik folder, it's an indicator that the auto-update did not complete successfully. (Please check your max_execution_time in php.ini.)
Either copy tmp/latest/piwik to your root piwik folder, or download latest.zip and extract. If you re-run the installer, select "reuse existing tables".
The error occurred almost immediately (less than 15 seconds), so it is not an issue of exceed max_ex_time in php(set to 60 seconds on my server).
Also the tmp/latest folder does not contain a piwik folder. The update seemed to complete normally after refreshing (eg updating piwik tables, etc)
Ok, I figured it out. The old CoreUpdater (in memory) is loading the new View.php. I think the fix is to instantiate the view earlier.