The issue appear after upgrading and old Apache2.2 to Apache2.4.

~# service apache2 restart

     * Restarting web server apache2                [fail] 
     * The apache2 configtest failed.

    Output of config test was:
    AH00526: Syntax error on line 11 of /etc/apache2/sites-enabled/www-mycompany:
    Invalid command 'RewriteLog', perhaps misspelled or defined by a module 
    not included in the server configuration

    Action 'configtest' failed.
    The Apache error log may have more information.

Earlier versions of mod_rewrite use RewriteLog and RewriteLogLevel directives. This functionality has been completely replaced by new per-module logging configuration like mentioned on apache docs

~# cat /etc/apache2/sites-enabled/www-mycompany | grep LogLevel
   LogLevel alert rewrite:trace3

To get just the mod_rewrite-specific log messages, pipe the log file through grep:

~# tail -f error_log|fgrep '[rewrite:'