iTunes backup also WhatsApp chats?
When WhatsApp backup to iCloud gets stuck

It's a 'bit late' but I recently experienced a similar problem to the one above, date June 2016.
For people like me who - for some reason - still have to change their iPhone 4 to 6s in 2017, you can bump into the problem that Whatsapp gets stuck while backing up on iCloud. It took me a while but I solved it eventually with the following steps:


Stop Whatsapp from being stuck: Settings > iCloud > switch off
Document Data &amp; WhatsApp
Delete your current Apple ID account on your iPhone 4 Create a new free Apple ID ON YOUR IPHONE 4: Settings > iTunes en Appstore > Create new free Apple ID 
Settings > iCloud > switch on Document Data &amp; WhatsApp Go to Whatsapp > Create backup 
On iPhone 6 log off with current Apple ID (and make sure you log off
with iCloud AND iTunes) and log in with the new ID you created on old
iPhone 4 
On iPhone 6 install Whatsapp from Appstore and import the backup from iCloud


iPhone 4 (iOs 7) has a problem with updated iCloud (Drive) but via this bypass you can do the trick.