How to upgrade Bitcoin Core Version on Raspberry PI? I want to upgrade my Bitcoin core version to latest release 0.16.1. The release docs say just copy over bitcoind/bitcoin-qt (on Linux). What does that mean? what to copy? Copying from where to where?

https://github.com/bitcoin/bitcoin/blob/master/doc/release-notes/release-notes-0.16.1.md#how-to-upgrade
They are referring to executable binary files, either the bitcoind daemon or the bitcoin-qt GUI app.   

The page with download links is https://bitcoincore.org/bin/bitcoin-core-0.16.1/

The only link for ARM (Raspberry Pi processor) is https://bitcoincore.org/bin/bitcoin-core-0.16.1/bitcoin-0.16.1-arm-linux-gnueabihf.tar.gz and expanding it 

$ tar -xf bitcoin-0.16.1-arm-linux-gnueabihf.tar.gz


I find these directories:

~/bitcoin-0.16.1$ ll
bin/
include/
lib/
share/

~/bitcoin-0.16.1$ cd bin
~/bitcoin-0.16.1/bin$ ll

bitcoin-cli*
bitcoind*
bitcoin-tx*
test_bitcoin*


I don't find a bitcoin-qt GUI version; perhaps they have not compiled one yet. But you can certainly use the command-line versions, bitcoind, bitcoin-cli and bitcoin-tx.

The place to put them is where they will be found from anywhere, for example, /usr/local/bin   or /usr/bin.