After Update "by hand" form 1.11 to 2.0.2 get errors

Hi,

after Update from 1.11.x to 2.0.2 I get the following messages:
Notice: Undefined index: log_writers in /piwik/core/Log.php on line 271 Warning: array_map(): Argument
#2 should be an array in /piwik/core/Log.php on line 273 Warning: Invalid argument supplied for foreach() in /piwik/core/Log.php on line 274

and the following:
Warning: file(/piwik/.git/HEAD): failed to open stream: No such file or directory in /piwik/core/SettingsPiwik.php on line 304

I run the update in following steps
- download piwik via wget and run unzip
- backup config files
- delete all old files in the vhost directory
- copy all new piwik files in the vhost directory
- request piwik application (https) and see this error messages
server is apache on debian squeeze, php 5.3.3-7 with Suhosin 0.9.32.1

What is going wrong or what I have do wrong?

Thank you for help.
Michael