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

Call Stack:
    2.3369     232888   1. {main}() /home/gongquiz_blog/www/index.php:0
    2.3370     234176   2. require('/home/gongquiz_blog/www/_common.php') /home/gongquiz_blog/www/index.php:2
    2.3372     268760   3. include_once('/home/gongquiz_blog/lib/common.php') /home/gongquiz_blog/www/_common.php:3
    2.3528    1141792   4. dbConn->__construct() /home/gongquiz_blog/lib/common.php:68
    2.3529    1158232   5. log_e() /home/gongquiz_blog/lib/common/dbConn.class.php:48
    2.3762    1351296   6. error_::log_e() /home/gongquiz_blog/lib/libf.php:564
    2.3796    1353008   7. error_::log() /home/gongquiz_blog/lib/common/error_.class.php:81