Protocol version 20 is now live on the testnet with release candidate v1.17.1-rc. This update brings several new features and improvements, including the implementation of IIP-8 for dynamic minimum commission, changes to validator score handling, and new indexing capabilities. This is a prerelease, so it's not on the mainnet yet. Testnet users and node operators should review the changes and prepare for potential downtime during migrations.

Protocol Updates

• Dynamic Minimum Commission (IIP-8): Dynamic minimum commission is now implemented across all networks. This aligns with IIP-8 and introduces a more flexible mechanism for setting validator commission rates. Stakers and validators should evaluate how this impacts reward structures.
• Validator Score Decoupling: A new feature flag, pass_calculated_validator_scores_to_advance_epoch, allows validator score calculation to be decoupled from score propagation in epoch advance transactions. When disabled, default scores are passed instead of locally computed ones. This flag is enabled on Devnet only.

Node Changes

• Epoch Indexing and Object Type Enhancements: Full nodes and validators now support epoch indexing, object type information for transactions, and type information for dynamic fields. This update requires a migration that may cause several minutes of downtime during node restarts. Operators should plan accordingly to meet their SLAs.

Indexer Updates

• Extended Statistics: The indexer now tracks dependencies for columns representing object types. Like the node migration, this update also requires downtime during the restart of the writer service. Operators should account for this when scheduling updates.

JSON-RPC and GraphQL Changes

• Improved Validator APY Calculations: Validator APY calculations now use a 7-epoch mean with outlier protection. This ensures more accurate and stable APY figures for stakers.
• Human-Readable Error Messages: JSON-RPC now resolves move abort errors into a more human-readable format, improving debugging and user experience.

CLI Improvements

• Config File Paths: The iota start command now uses path values (db-path, genesis-file-location, migration-tx-data-path) from network.yaml and fullnode.yaml config files.
• Environment Selection: A new --client.env flag for client and move subcommands lets users specify an environment for a single CLI command, streamlining workflows.

Rust SDK Changes

• WalletContext Updates: The WalletContext::new function now only requires the path to the config. Additional configurations like timeout and max concurrent connections can be set after the context is created, providing more flexibility for developers.

Wallet v1.5.5 Release

The latest stable wallet release (v1.5.5) includes support for calculating the effective commission rate as per IIP-8. This ensures the wallet aligns with the dynamic minimum commission changes introduced in protocol v20. Developers should update to this version to ensure compatibility.

Operator Considerations

Both the node and indexer updates require migrations that may result in several minutes of downtime. Node operators should stage these updates carefully to avoid SLA violations. Testnet participants should monitor validator performance and staking rewards to evaluate the impact of IIP-8 and the updated APY calculations.

For details, check the full protocol changelog.

Sources: wallet-v1.5.5, v1.17.1-rc, wallet-v1.5.4