Drupal 8.x

I did all the updates from beta 14 ro rc3 without a problem.
Today I wanted to update to 8.0.0 and got this error:

An AJAX HTTP error occurred.
HTTP Result Code: 500
Debugging information follows.
Path: /update.php/start?id=10&op=do_nojs&op=do
StatusText: Internal Server Error
ResponseText:

This was what I got before it all went wrong:

The version of Drupal you are updating from has been automatically detected.
2 pending updates
system module

I am new to drupal, so any help would be appreciated in advanced. My requirements are as follow.

1 happened in signed in user environment.
1 :" there must be groups. and they will be assigned under one user (role: manager) only he can manage the user (create,update,read and delete)" - need to be solved

*** There will be a user with (admin permission) will be able to manage groups including manager *** solved**

I am trying to copy a file (and register it in file_managed) using a very popular code snippet that used to work in D7 and follows the rules for D8:

$data = file_get_contents('https://www.drupal.org/files/druplicon.small_.png');
$file = file_save_data($data, 'public://druplicon.png', FILE_EXISTS_REPLACE);

Couldn't be too much simpler, right? But I get the following error:

Hey there,

I've set up an clean installation of Drupal 8.0.0. The setup worked fine without any problem. But when I try to install any new module via /admin/modules/install or admin/theme/install the following error shows up:

The website encountered an unexpected error. Please try again later.
Drupal\Core\Form\EnforcedResponseException: in Drupal\Core\Form\FormBuilder->buildForm() (line 349 of core/lib/Drupal/Core/Form/FormBuilder.php).

Do you have any ideas on this?

Thank you!

I installed drupal 8. Now i want to divide the users in it to a hierarchy structure such that -

1) Admin can edit all users.
2) Group 1, Group 2, Group 3 are under admin.
3) All 3 groups have subgroups.
4) Group 1 admin cannot edit other groups or group members. Group 1 admin can edit only the menbers and sub groups under Group1.

Any module available for the above process.

Hi All,