Commonly faced bugs/tickets in realtime ?

Hi

can any one please post me some information about commonly we are facing bugs/tickets in realtime from fun/client .

i am new to Webdynpro ABAP .actually idnt know which type of bugs will come .

i want to know Some information which type of tickets we receive in real time .

Could you anybody please send me some bugs in simple words .

thank you

regards

satish