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Tezos X

Action required

• Previewnet has been reset — all prior state is gone. Address identity now lives inside the account record, and the old identity data can't be carried over, so the network was rebuilt from genesis. Every account, balance, and contract deployed before this release is cleared: re-fund your accounts from the faucet and redeploy your contracts.
• The rollup address changed. The reset produced a fresh smart-rollup address — update any hardcoded reference in installer configs, indexers, and node setups. The current value is shown live in the All endpoints section below and in the canonical repo ↗.
• Newly originated contract addresses are now computed like Tezos L1 and shift by one from before. Every originated address — including those created through cross-runtime calls — is different now; don't reuse a pre-reset address.
• Native operations must reference a recent Tezos X block, not a Tezos L1 block. This closes a replay hole where the same signed operation could be reused on another network, and it restores transaction freshness. Operations sent through the delayed inbox are affected — update tooling that builds native operations to anchor on a recent Tezos X block.
• “CRAC” is now spelled out as “cross-runtime call” across headers, events, tags, error messages, and logs. Because event signatures change with the new names, log indexers must be updated to track both the new signatures and the new field names.
• Gas costs have changed. Many Michelson operations were re-measured on the new runtime, some previously-free operations are now charged, and cross-runtime gas was rebalanced. Reported gas and gas estimates change for affected contracts — refresh any cached gas estimates.
• Two legacy shortcuts were removed. The old direct-transfer selector on the runtime gateway and the old %default transfer entrypoint are gone — use the generic call entrypoint instead. Alias forwarders created before this change need to be re-created to keep working.

Security

• Signature malleability is blocked. Alternate-but-equivalent encodings of a signature are now rejected, so a contract that relies on signature bytes for anti-replay can no longer be fooled by a reworked twin of a valid signature.
• Transaction-hash malleability is blocked. A signed transaction now has a single valid encoding, so it can no longer appear under several different transaction hashes — protecting wallets, indexers, and bridges that track a transaction by its hash.
• Fee-griefing on reveal batches is fixed. A batch whose declared public key doesn't match its source is now rejected up front, before any fee is charged, so an attacker can no longer force fees onto a solvent account.
• Result spoofing on the gateway is fixed. Only the contract actually being dispatched can deposit its result, so a contract called along the way can no longer inject its own data as someone else's result or block a legitimate one.
• Contracts can no longer forge access to another contract's storage. Passing or originating with a borrowed big-map identifier is now rejected, matching Tezos L1.
• Duplicate internal operations are rejected. A contract could previously duplicate an operation value and have it run twice (a double transfer or origination); such duplicates now roll back the whole operation, matching Tezos L1.
• Out-of-gas in a read-only cross-runtime call now fails safely, returning a clear out-of-gas error instead of an empty result — so a caller can't be pushed down a fallback path by exhausting the target's gas.
• Attacker-controlled data can no longer bloat block metadata cheaply. Error and revert payloads carried across runtimes are now charged for their size before being stored, and several operations were reworked so oversized or deeply-nested values run out of gas instead of overwhelming the kernel. A separate denial-of-service path was closed off behind a feature flag.

New

• Michelson contracts can read live EVM block data. A call from the Michelson interface into an EVM contract now sees real block values — base fee, gas limit, randomness, gas price, and more — instead of placeholder zeros. Fee handling is unchanged.
• Aliases share a single upgradable implementation. Aliases no longer carry their own copy of the forwarder code; they all resolve to one shared implementation that can be upgraded for every alias at once, with safeguards so existing contracts keep working.
• New storage-space queries. You can now read how much storage space a contract uses and has paid for, mirroring the equivalent Tezos L1 queries.
• Clearer cross-runtime frames in receipts. Each cross-runtime call is now bracketed by a matching start and end marker, so tools can reconstruct the full call tree from a receipt.
• The kernel recovers from software failures. A recovery procedure protects the network against internal crashes, and a transaction shown to trigger such a crash is dropped from the delayed inbox instead of stalling the network.

Improvements

• Caller identity is now correct across runtimes. The original sender is carried through chains of cross-runtime calls, so identity checks resolve correctly even across an EVM → Michelson → EVM round-trip.
• Storage burn now matches Tezos L1. Big-map usage counts toward a contract's storage footprint, genesis and bootstrap contracts start with the right storage accounting, and storage costs from cross-runtime work are billed to the correct payer.
• Cross-runtime gas is fairer and consistent. Rounding no longer leaves a tiny remainder uncharged, and a call originating on the Michelson side is now charged the same as the equivalent call originating on the EVM side.
• Recursive cross-runtime loops fail cleanly. A self-recursive gateway cycle now ends as a normal operation failure instead of exhausting memory, and the rest of the block — including deposits — is preserved.
• The Michelson runtime is faster, touching fewer storage entries when reading account balances and storage accounting.
• Cross-runtime events are self-consistent, reporting a stable target address and the correct source runtime, so tools no longer split one contract into two identities.
• Block production is more robust. The sequencer now budgets blocks by their actual serialized size, avoiding block-production failures from oversized output.
• Delayed-inbox operations behave like the others. Michelson contracts run there now see the right chain id, and fee checks and gas refunds are applied correctly.

Fixes

• Deposits are refunded on revert. A cross-runtime deposit is now returned when the receiving call reverts, so funds can no longer be stranded while the receiver goes uncredited.
• No more leftover storage entries. A fully reverted or fully drained bridge claim no longer leaves an empty ticket entry behind, and an alias forwarder created during a call that then runs out of gas is properly rolled back instead of leaking into a later call's receipt.
• Gas reporting on failures is accurate — a failed cross-runtime call now reports the gas it actually consumed rather than a maximum value.
• Receipts are correct. Gas totals, error placement, operation ordering, and internal-operation limits now match Tezos L1, and errors are recorded once rather than twice.
• Many small Michelson divergences from Tezos L1 were fixed in how scripts are type-checked and how values are parsed and compared, so scripts behave the same on Tezos X as on Tezos L1.
• Tickets are temporarily disabled in the Michelson runtime and can be re-enabled later once the conditions for doing so are agreed.