magento - Fatal error: Class 'Varien_Autoload' not found -

during deployment of magento site got following warning , error:-

warning: include_once(varien/autoload.php): failed open stream: no such file or directory in /home/xxx/subdomain/stage/app/mage.php on line 50  warning: include_once(): failed opening 'varien/autoload.php' inclusion (include_path='/home/xxx/subdomain/stage/app/code/local:/home/xxx/subdomain/stage/app/code/community:/home/xxx/subdomain/stage/app/code/core:/home/xxx/subdomain/stage/lib:.:/usr/lib/php:/usr/local/lib/php') in /home/xxx/subdomain/stage/app/mage.php on line 50  warning: include(varien/autoload.php): failed open stream: no such file or directory in /home/xxx/subdomain/stage/app/code/core/mage/core/functions.php on line 68  warning: include(): failed opening 'varien/autoload.php' inclusion (include_path='/home/xxx/subdomain/stage/app/code/local:/home/xxx/subdomain/stage/app/code/community:/home/xxx/subdomain/stage/app/code/core:/home/xxx/subdomain/stage/lib:.:/usr/lib/php:/usr/local/lib/php') in /home/xxx/subdomain/stage/app/code/core/mage/core/functions.php on line 68  fatal error: class 'varien_autoload' not found in /home/xxx/subdomain/stage/app/mage.php on line 53 

i have set permission 777 , set include_path correctly , there lib folder inside includes not working.

please suggest how solve error. thank you.