i want to upgrade my Bluetooth from v3.0 to v4.0

[AC Question]

i want to upgrade because my mi band 2 needs a bluetooth v4.0

 

[anon(632115)]

That's a pretty new device. If it had the chipset for v4.0 I'm sure it would have been activated. I doubt you can update it, sorry

 

[hallux]

I have the feeling the OP is looking to upgrade the Bluetooth on their phone to 4.0 to support the mi band. The short answer is that it can't be done. It's not as simple as a software patch, it needs to be supported on a hardware level.