Site completely crashes after upgrading from 2.10 to 2.11 (no replies)

So my site says 2.11.0 is available and I should upgrade.

I don't like sites updating themselves, but I was tempted by the "one click" thing as I was feeling lazy. So I changed the permissions on the site's files and let it run. All the way to a white screen of death. The logs read:

[Thu Feb 19 11:07:45 2015] [error]  PHP Fatal error:  Class 'Piwik\\Scheduler\\Task' not found in /var/www/mysite/piwik/plugins/UserCountry/GeoIPAutoUpdater.php on line 36, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP Stack trace:, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   1. {main}() /var/www/mysite/piwik/index.php:0, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   2. require_once() /var/www/mysite/piwik/index.php:27, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   3. Piwik\\FrontController->init() /var/www/mysite/piwik/core/dispatch.php:30, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   4. Piwik\\Plugin\\Manager->loadActivatedPlugins() /var/www/mysite/piwik/core/FrontController.php:335, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   5. Piwik\\Plugin\\Manager->loadPlugins() /var/www/mysite/piwik/core/Plugin/Manager.php:103, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   6. Piwik\\Plugin\\Manager->reloadActivatedPlugins() /var/www/mysite/piwik/core/Plugin/Manager.php:670, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   7. Piwik\\Plugin\\Manager->loadPlugin() /var/www/mysite/piwik/core/Plugin/Manager.php:859, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   8. Piwik\\Plugin\\Manager->makePluginClass() /var/www/mysite/piwik/core/Plugin/Manager.php:920, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP   9. require_once() /var/www/mysite/piwik/core/Plugin/Manager.php:948, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate
[Thu Feb 19 11:07:45 2015] [error]  PHP  10. require_once() /var/www/mysite/piwik/plugins/UserCountry/UserCountry.php:23, referer: https://mysite/piwik/index.php?module=CoreUpdater&action=oneClickUpdate

Happily I had a backup of the files so I restored, and got the site running again.

Then I tried the manual method; deleted the piwik dir, put the new one in place. Copied back the config.ini file. Reloaded the site to a message "Your Piwik database is out-of-date, and must be upgraded before you can continue.". Following the command line, I did

/path/to/piwik/$ php console 'core:update'
[InvalidArgumentException]
  There are no commands defined in the "core" namespace.

I did the db upgrade through the web interface and it then worked.

This is my first piwik upgrade and it turned out to be a lot more than "1 click". Did I do anything wrong or is this normal? :-/