[Mediawiki-l] PHP Fatal error: Cannot instantiate abstract class SqlBagOStuff

[Stefan-Michael Guenther]

Hello,

after a hardware failure, we restored the Wiki-Directory (MediaWiki 
1.15.5) and the database (MySQL 5.0.18) from our backup.

But instead of the wiki pages we only get the following messages in the 
php.log:

[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Notice: 
Undefined variable: wgExtensionAssetsPath in 
/srv/www/htdocs/w/includes/Setup.php on line 43
[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Notice: 
Undefined variable: wgUseInstantCommons in 
/srv/www/htdocs/w/includes/Setup.php on line 132
[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Notice: 
Undefined variable: wgDebugPrintHttpHeaders in 
/srv/www/htdocs/w/includes/Setup.php on line 187
[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Notice: 
Undefined variable: wgHtml5Version in 
/srv/www/htdocs/w/includes/Setup.php on line 248
[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Notice: 
Undefined variable: wgHtml5 in /srv/www/htdocs/w/includes/Setup.php on 
line 248
[Tue Mar 29 23:53:03 2011] [error] [client 127.0.0.1] PHP Fatal error: 
Cannot instantiate abstract class SqlBagOStuff in 
/srv/www/htdocs/w/includes/ObjectCache.php on line 85

The include_path in php.ini (PHP 5.2.17) contains the following directories:

include_path = 
".:/usr/share/php5:/usr/share/php5/PEAR:/srv/www/htdocs/w/includes:/srv/www/htdocs/w:/opt/php-5.2.27/lib"

Obviously there's something missing, but what??

Thanks for any suggestions or hints,

Stefan