If you already run a BLAKE2b Knots node
Keep your existing Bitcoin data folder. You do not need to download the chain again or move your coins.
If you are still on Bitcoin Core or older Knots
Install Knots 29.4.2. Download official builds from bitcoinknots.org. Other options are on the mainnet solo mining guide. Source is at github.com/bitcoinknots/bitcoin. Your current software may have followed the legacy SHA256d chain. On startup, this release usually notices those extra blocks, walks back to the fork, and then downloads the BLAKE2b chain.
A pruned node deletes old blocks to save disk space. If you waited so long that those walk-back blocks are already gone, or the node followed invalid blocks after a late upgrade, rebuild the node and download the chain again. This release may ask at startup whether that resync is required.
Everyone
- You do not need to move your bitcoin to keep it. Coins created before the fork remain spendable.
- If you intend to sell, gift, or spend the fake “bitcoins” on the SHA256d altcoin launched by former miners, use a wallet that supports the opt-in
SIGHASH_UNIFIEDsighash, then send your bitcoins to yourself with that format on this chain first. Wait for the payment to confirm. See What is SIGHASH_UNIFIED? - After the BIP-110 softfork, Bitcoin Core and older Bitcoin Knots still use the legacy SHA256d algorithm and follow a different blockchain. Today's ordinary Knots download is not enough; you need the BLAKE2b version.
- Miners should use DATUM against a Knots node. Wallets and exchanges have additional work; see the FAQ and businesses page.