Solana activated the txv1 feature gate on mainnet at the start of epoch 1035 on September 15, 2026 at approximately 01:00 UTC, raising the network’s maximum transaction size from 1,232 bytes to 4,096 bytes, according to an official upgrade note published by Solana. The change is defined in SIMD-0296 and delivered through the v1 transaction format introduced in SIMD-0385. Solana said the larger envelope is designed to unlock workloads that previously had to be split across several chained transactions, while the existing v0 and legacy formats continue to work unchanged.
What the 4,096-Byte Limit Unlocks
Solana framed the increase as a headroom gain rather than a breaking change. Work that previously had to be divided into several chained transactions — zero-knowledge proofs such as those used by Confidential Transfers, large multisignature operations and batched programs — can now land as a single atomic transaction, which means fewer signatures to pay for and one confirmation instead of several. Because v0 and legacy transactions remain unchanged, wallets and applications that do not need the extra room keep working exactly as they do today, and the note stresses that nothing about how users approve, sign or send a transaction changes.
Node Operators Face a Migration Window
The feature is live on mainnet, testnet and devnet, but Solana said some infrastructure needs a specific release. RPC nodes must upgrade to Agave v4.2.2 or later; earlier builds downgrade v1 messages to v0 on the way into storage, which zeroes out the compute budget and misreports the version. Jito-Solana validators also need v4.2.2 or later, because a leader running an older build will not assemble v1 transactions into its blocks. The note points to a version matrix recording the first release of every dependency that handles v1 transactions, alongside a runnable code example for sending, decoding and indexing them.
Another Step in a Busy Year of Solana Upgrades
The transaction-size increase follows a run of mainnet changes aimed at throughput. Solana earlier raised its block capacity to 100 million compute units on mainnet and separately cut its slot time to 350 milliseconds in the first reduction since genesis. Together the changes signal the network’s push to support larger and more complex workloads, including the proofs and batch operations that the bigger transaction envelope is designed to accommodate.
