How to transfer whatsapp chats from old device to a new device..... try this trick..

As convenient as the popular WhatsApp messenger may be, there's always a catch: You can't really use the app on more than one device at a time. This is quite annoying when you have multiple smartphones or you pick up the latest and the greatest device. But wait. What if I told you that could easily transfer over your chat history to a new device? Here's the low-down on how to do it.

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When I finally received my new HTC One into my awaiting hands, I was faced with a problem: what do I do with my WhatsApp messages that had accumulated in the last year on my old smartphone? For some people, this really isn't much of an issue. Delete everything
from the old smartphone. Transfer over to new one. Start over. Unfortunately, I don't fall into this group and really wanted to be able to save my chat history.
Luckily, I found a little trick on how I could transfer my entire chat history onto my new phone and seamlessly chat where I had left off the night before. If you also want to save your chats and continue as normal on a different device, simply proceed as follows:

• Creat a backup of your chat history on your old phone. To do this you open the settings menu of WhatsApp, tap on "Chat Settings" and then tap "backup chat history".
• Connect your smartphone via USB cable to the PC and navigate in the internal memory of the device to the folder "WhatsApp / Databases". Here are all the backup files saved with the date (eg msgstore-2013-05-29.db.crypt). Copy the file with the latest date on your PC, such as on the desktop. 
• Install WhatsApp on your new device. Important: Do not start the app!
• Connects your new device via USB to the PC. If you've downloaded WhatApp onto your new device, a folder "WhatsApp / Databases" should be already there. If not, you can manually create it. Then you copy over the backup file msgstore-YYYY-MM-TT.db.crypt into this folder.

Then start your WhatsApp on your new phone and verify your phone number. You should now get a notification that a message backup was found. Just click on "Restore" tap, done.    
After a few seconds, all messages are returned. Then you still have to enter a name and possibly set a profile picture, and already you have all the old chats on your new smartphone and you can continue exactly where you stopped before.
Tada! Relatively simple fix and easy to do when transferring over to a new device.

Source: AndroidPit