Alphanet v3 has been pushed to GitHub and is up and running.

Alphanet v3 is a hardfork, so all previous blockchain data must be discarded. This is a hardfork due to an update to the serialization implementation BFieldCodec.

Since alphanet coins are worthless and alphanet-v3 is a restart of the blockchain from genesis, you can simply reset you node by running rm -rf ~/.local/share/neptune/ assuming default configurations. If you want to be a bit more finegrained in what you delete and you want to keep your receiving address see this guide: https://github.com/Neptune-Crypto/neptune-core/#restarting-node-from-the-genesis-block

So, to update, the following commands should do it:

• First navigate to the directory, where you have the neptune-core git repo stored. Then:

rm -rf ~/.local/share/neptune/
git pull
cargo install --path .
RUST_BACKTRACE=1 RUST_LOG='info,tarpc=warn' neptune-core --mine --throttled-mining --peers 51.15.139.238:9798 --peers 139.162.193.206:9798

Please note that you normally do not want to delete your wallet.dat, incoming_randomness.dat, and outgoing_randomness.dat files. Basically, you should normally never delete anything in your wallet directory.