Fatal error: Class 'Client' not found in /home/gongquiz_blog/lib/common/error_.class.php on line 92

Call Stack:
    2.3146     237336   1. {main}() /home/gongquiz_blog/www/index.php:0
    2.3148     238624   2. require('/home/gongquiz_blog/www/_common.php') /home/gongquiz_blog/www/index.php:2
    2.3151     272792   3. include_once('/home/gongquiz_blog/lib/common.php') /home/gongquiz_blog/www/_common.php:3
    2.3300    1143560   4. dbConn->__construct() /home/gongquiz_blog/lib/common.php:68
    2.3303    1159960   5. log_e() /home/gongquiz_blog/lib/common/dbConn.class.php:48
    2.3329    1354472   6. error_::log_e() /home/gongquiz_blog/lib/libf.php:563
    2.3333    1356192   7. error_::log() /home/gongquiz_blog/lib/common/error_.class.php:81