hey i wanna ask why my iphone cannot be back up? always say fail as iphone is disconnected.

hi what i mean is whenever i want to sync my iphone to backup my iphone, in the midst of the process it will always pop up a message saying iphone cannot be backup as iphone is disconnected. Yes i check my drive c is enough to backup.

iOS 8.4 . I try another port already. But I didn't try another lighting cable as my lightning cable is original so I think it should be works?? My iTunes version is the latest just updated ytd. I try to back up the whole day from yesterday till now also cannot. The msg is still the same saying my iPhone disconnected. I just realized that I had not back up my iPhone before since I bought it be coz of this msg. Is it because my iPhone use too much memory ? I'm using 128gb but now only approximately 50gb left.

Authorized already.

Hi, I had try and it is also didn't work. I try to use another laptop it still the same cannot back up but this time instead of disconnected it say a session cannot be start with the iPhone.

nope i cant find the apple folder

i had successfully made a backup to a new pc but when i restore,from backup the estimating time remaining keep on running for about half an hour already,is this normal?