IOTA has released Mainnet v1.35.2, introducing Protocol Version 39 alongside a substantial collection of improvements to consensus reliability, validator operations, transaction processing, network synchronization and security. The November 4 release represents another important infrastructure upgrade as the network continues refining the systems responsible for processing and validating transactions.
The update includes changes across validators, full nodes, indexers, JSON-RPC, GraphQL, the Rust SDK and gRPC services. Rather than focusing on a single performance improvement, the release addresses several operational challenges, including synchronization delays, transaction validation inconsistencies, security vulnerabilities and more predictable network behaviour.
One of the most important changes concerns the activation schedule. Protocol Version 39 can be enabled on mainnet no earlier than November 5, 2026, at 07:42 UTC, corresponding to the beginning of epoch 549. IOTA has instructed validators to update their software before this transition. Validators that fail to upgrade could be removed from the committee once the upgrade threshold is reached, resulting in lost rewards for both validators and their delegators.
Protocol 39 Changes Consensus and Validator Requirements
Protocol Version 39 introduces several changes intended to improve the reliability and consistency of IOTA’s consensus process. One notable improvement concerns consensus message deduplication. Validators will now skip a message as a duplicate only when an earlier message with the same key was successfully recorded as processed or passed verification in the same commit. This helps ensure that validators reach consistent decisions when handling repeated messages.
The upgrade also improves random beacon functionality on devnet and testnet. When distributed key generation misses its timeout round, the process can continue running and potentially restore randomness during the same epoch rather than remaining disabled until the next epoch. This provides a more resilient approach to handling interruptions in the randomness-generation process.
Validator participation requirements are also changing. The minimum joining stake increases to 6 million IOTA, while the low-stake and very-low-stake thresholds move to 5.5 million and 5 million IOTA, respectively. These adjustments redefine the stake requirements used by the network when assessing validator participation.
Security improvements extend to multisignature transactions. Under Protocol Version 39, a multisignature committee combining Ed25519 with other key schemes will only be accepted when every committee member has signed. The release also introduces stricter handling of Groth16 verification keys, preventing certain mismatched inputs from proceeding through verification functions.
For node operators, several changes target synchronization and execution reliability. The release fixes checkpoint execution delays that could occur when validators received consensus checkpoints while state synchronization was still downloading earlier checkpoint contents. It also improves fast commit synchronization by processing responses in chunks rather than holding entire responses in memory, helping control resource consumption.
IOTA Improves Node Security, Indexing and Developer Infrastructure
The release includes important security maintenance, including updates to the Rustls and Quinn protocol dependencies to address multiple identified security advisories. IOTA has also improved traffic management by introducing more detailed client-blocking logs and additional IPv6 traffic controls. These changes give node operators better visibility into suspicious connections and more flexibility when managing network access.
Another operational change removes the previous delegation of blocks to a remote firewall. The associated configuration option is now ignored, and its related metrics have been removed. The network’s traffic-control system also receives clearer rules for blocklist time-to-live settings and IPv6 address-prefix handling.
Transaction processing receives additional safeguards through deterministic validation. Transactions attempting to use inputs that were already consumed, deleted or inconsistent with the state recorded at their consensus commit now fail immediately with a specific error. This replaces repeated retries that previously returned a less precise object-not-found response.
The indexer and API infrastructure also receive significant improvements. Historical checkpoint files will no longer be repeatedly downloaded under certain ingestion conditions, while ingestion processes now shut down gracefully when their maximum backoff period is reached. JSON-RPC responses have also been improved to communicate the oldest available checkpoint when historical data has been pruned, helping applications distinguish unavailable historical information from genuinely missing objects.
Developers receive additional improvements across GraphQL, Rust SDK, CLI and gRPC services. GraphQL responses now include a minimum SDK version header, while the Rust SDK introduces an oldest-available-checkpoint field that developers must account for when updating affected applications. The gRPC interface also receives better timeout handling, TLS connection controls and stricter transaction and event filter limits.
Overall, v1.35.2 represents a broad infrastructure upgrade rather than a cosmetic software release. Protocol 39 changes how validators handle consensus messages, establishes updated staking thresholds and strengthens transaction verification, while improvements across nodes and developer interfaces address practical reliability issues. The immediate priority is successful validator adoption before the November 5 activation window, after which the network can begin operating under the new protocol rules.
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