That's why I had to do an "ln -s /var/log/apache2/ /usr/lib/apache2/logs" after upgrading apache from 2.0.59 to 2.2.4 to get it up and running with subversion. The error msg is : /var/log/apache2/error_log:[Sat Sep 08 15:50:12 2007] [error] (2)No such file or directory: could not open transfer log file /usr/lib/apache2/logs/svn_logfile. Reproducible: Always
the default mod_sav_svn configuration does not include any logging configuration... probably somewhere in your custom config