Upgrade from an D7-distribution to D8 - Win7, XAMPP 1.8.1

I have tested the d7 to d8 upgrade path on my local dev system and I get two error-messages.

Win7-64bit german client - XAMPP 1.8.1 (PHP 5.4.7, Apache 2.4.3, MySQL 5.5.27)

XAMPP is properly installed in path: C:\XAMPP\.

My steps:

1. I have made a fresh install of the german D7.22 (download from http://www.drupalcenter.de/files/drupal-7.22-DE.zip), profile Drupalcenter with german language.
   
   1. The D7 from drupalcenter.de, which is the "german d.o.", installs the module "dcblock", which shows a static block ("Deutschsprachige Drupal-Version: Drupal Center") in footer.
2. Then I put the site into maintenance mode.
3. Then I disable and uninstall the module "dcblock".
4. Then I delete all files outside the 'sites' directory.
   
   1. Using the UI of D7, I cannot disable and uninstall the profile "Drupalcenter" like a module.
   2. The format of the .info files has changed from D7 to D8. Therefore the old files (modules, profiles) are not used within D8. It makes no difference whether they are still there or not after the ungrade.
5. Then I copied all files from Drupal 8.x-dev - Last updated: 2013-Mai-11 in the root directory.
6. Then I have made the settings.php file writeable.
7. Then I started http://www.example.com/core/update.php.
8. The upgrade is successful.

But now I get an ugly error message:

Notice: Undefined index: name in system_requirements() (line 42 of core\modules\system\system.install).
Notice: Undefined index: version in system_requirements() (line 44 of core\modules\system\system.install).

With the new option ('http://www.example.com/admin/config/development/logging') "Error messages to display: - All messages, with backtrace information" I get:

Notice: Undefined index: name in system_requirements() (line 42 of core\modules\system\system.install).

system_requirements('runtime')
call_user_func_array('system_requirements', Array)
Drupal\Core\Extension\ModuleHandler->invokeAll('requirements', Array)
module_invoke_all('requirements', 'runtime')
system_status()
call_user_func_array('system_status', Array)
Drupal\Core\EventSubscriber\LegacyControllerSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1)
Drupal\Core\HttpKernel->handle(Object, 1, 1)
Symfony\Component\HttpKernel\Kernel->handle(Object)
drupal_handle_request()

Notice: Undefined index: version in system_requirements() (line 44 of core\modules\system\system.install).

system_requirements('runtime')
call_user_func_array('system_requirements', Array)
Drupal\Core\Extension\ModuleHandler->invokeAll('requirements', Array)
module_invoke_all('requirements', 'runtime')
system_status()
call_user_func_array('system_status', Array)
Drupal\Core\EventSubscriber\LegacyControllerSubscriber->Drupal\Core\EventSubscriber\{closure}()
call_user_func_array(Object, Array)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1)
Drupal\Core\HttpKernel->handle(Object, 1, 1)
Symfony\Component\HttpKernel\Kernel->handle(Object)
drupal_handle_request()

Note:
Many D7-sites use a distribution. I think, this errors should be solved, before D8 comes to be an official release.

Something is wrong or I have done something in a wrong way.

Wusel