Testnet release v1.16.2-rc is live, bringing protocol version 19 and significant updates across the board. This is a prerelease, so it's not on mainnet yet. Key changes include the introduction of ChangeEpochV4, Starfish consensus on testnet, and updates to scoring-based rewards. If you're running an indexer or custom tooling, you'll need to upgrade dependencies to avoid disruptions.

Protocol Updates

• Protocol v19 is now active on testnet. The big change is the new ChangeEpochV4 transaction type, which modifies how epochs are handled and rewards are distributed. This will appear in checkpoints as soon as the protocol activates. Custom indexers must update the iota-data-ingestion-core dependency to v1.16.x.
• Gas price feedback has been adapted to the congestion limit overshoot feature and enabled on devnet. A new mechanism for gas price feedback using randomness is also live on devnet.
• Metadata handling: The metadata_in_module_bytes flag now allows IOTA-specific metadata to be added to serialized bytecode.
• Package metadata: The publish_package_metadata feature creates immutable objects at publish/upgrade time when specific attributes (like authenticator functions) are in the source.
• Abstract Account authentication: The move_auth flag and max_auth_gas protocol parameter enable Abstract Account authentication and define gas budgets for it.
• Starfish consensus is now active on testnet, replacing the previous consensus protocol.
• Passkey authentication is enabled on mainnet, improving account security.
• Misbehavior reporting: A new ConsensusTransactionKind variant supports misbehavior reports. This includes validation, dissemination, and scoring metrics for authorities. The Scorer component tracks metrics, reports, and scores, and new scoring formulas adjust validator rewards based on behavior.
• Advance Epoch updates: A new version of the advance epoch transaction allows reward modifications based on validator scores. Score-based rewards are active on devnet with feature flags (calculate_validator_scores and adjust_rewards_by_score) controlling their behavior.

Node Changes

• Indexes pruner: Authority store now includes an indexes pruner.
• Abstract Account authentication: Enabled on devnet for validators and full nodes.
• Scorer component: Tracks misbehavior metrics and validator scores.

Indexer Changes

• The new ChangeEpochV4 system transaction can appear in checkpoints on networks with score_based_rewards or calculate_validator_scores enabled. Update your iota-data-ingestion-core dependency to v1.16.x to ensure compatibility.

JSON-RPC Updates

• Dry run transactions now return error source information.
• The next_cursor field is no longer set if has_next_page is false.

CLI Updates

• New iota keytool commands:
  • tx-digest: Computes a digest for base64-encoded transaction bytes.
  • sign-raw: Signs raw transactions.
  • decode-sig: Decodes base64-encoded signatures.
• Abstract Account support:
  • KeyStore can store account addresses.
  • New commands: iota client add-account, iota client sign.
  • --auth-call-args and --auth-type-args options for iota client and iota client ptb.

Rust SDK Updates

• New MoveAuthenticator variant for GenericSignature supports Abstract Account authentication.
• get_owned_objects() now supports more efficient select_gas() implementations without fetching unnecessary pages.

Testnet users should upgrade to v1.16.x immediately to avoid issues with the new protocol features, especially if you're running custom indexers. Full details are in the release notes.

Sources: v1.16.2-rc, v1.16.1-rc