This 4.0.0 release represents “The Hardening” protocol upgrade and thus contains breaking changes! .
The Hardening protocol upgrade will be activated on block # 417,792. Initial difficulty for the block is set to “6f98d5555555” (in hex), which is corresponding to ~ 1TH/s hashrate.
- Autolykos 2 PoW scheme. It has non-outsourceability being switched off, table size growing with time, possible memory optimizations fixed.
- Merkle tree of transactions now also committing to transaction witnesses (a SegWit-like construction).
- possibility to enhance header structure via velvet forks added
Also, sigma-interpreter (ErgoTree interpreter) dependency updated to 4.0. Full details: ScorexFoundation/sigmastate-interpreter#712 , most important for the Ergo protocol are:
- activatedScriptVersion field added to execution context (ErgoLikeContext)
- ErgoTree interpreter is now skipping validation for scripts if activated script version is higher than interpreter supports (so old nodes are skipping validation on soft-forks when 90+% mining power activated the ErgoTree upgrade). See changes in Interpreter.verify()
- v4.0 can support AOT -> JIT switch as v5.0 soft-fork
Upgrade from 3.3.4 and on - just replace old jar with the new one.
3.3.0 - 3.3.3 - full resync is needed for MacOS X (leave /wallet/keystore folder where encrypted seed is stored). Also, please see upgrade notes for 3.3.4 if you are restoring pre-3.3.4 mnemonic Release Ergo Protocol Reference Client 3.3.4 · ergoplatform/ergo · GitHub
3.2.x - unlock wallet on the first 4.0.0 node run and do wallet rescan with /wallet/rescan API call
3.0.x && 3.1.x - full resync is needed (leave /wallet/keystore folder where encrypted seed is stored)