Cronos schedules v1.8 mainnet upgrade with breaking integration changes

Cronos scheduled its EVM mainnet to move to software version 1.8 on October 22, bringing a newer execution stack and several changes that can break integrations if operators are not prepared. As of Coinburn’s midday publication window, the opened primary records established the date and upgrade plan but did not establish that the coordinated change had completed.

That distinction matters because the package changes transaction admission, cross-chain functions and JSON-RPC behavior. Cronos Labs announced the date on October 14, while the project’s GitHub release—published September 24—still warns operators not to install the binary before the coordinated upgrade process.

What version 1.8 changes

Cronos Labs says version 1.8 introduces an optional application-side mempool. Instead of leaving all pending-transaction management to the CometBFT consensus layer, node operators can let the application apply custom checks before block construction. The setting is optional: existing configurations can continue using the prior path, so deployment of the binary does not mean every node immediately adopts the new mempool.

The release also embeds Block-STM parallel execution in the upgraded Cosmos SDK stack. Parallel execution can process non-conflicting transactions at the same time, while conflicting work is re-executed sequentially. Cronos recommends the parallel engine for validators, RPC infrastructure and archive nodes, but its announcement does not provide independently measured post-upgrade mainnet performance.

The package moves Cronos to Cosmos SDK 0.54.3, IBC-Go 11, CometBFT 0.39 and go-ethereum 1.16.9. Cronos says the go-ethereum change enables the Osaka hard fork on its chain. Those version numbers identify bundled software; they do not show how widely the new binary has been adopted across the validator set.

Integrators face concrete breaking changes

The operational effects extend beyond throughput. According to the Cronos announcement, the SendCroToIbc function becomes restricted to authorized contracts, Interchain Accounts are removed and the MsgTurnBridge message is no longer supported. Applications relying on those paths may need changes at the upgrade height.

Cronos also says version 1.8 enforces a minimum gas cost for calldata-heavy transactions and begins applying the JSON-RPC transaction-fee cap to eth_sendRawTransaction. The project’s migration guidance tells RPC operators to review that setting before the switch. These are configuration and compatibility issues, not evidence of a security incident.

The release expands support to more than 80 Ethereum API methods and describes compatibility as above 90%. Both figures are project-supplied feature counts in the September 24 release and October 14 announcement, not results from an independent interoperability test. Similarly, the project’s statement that the package contains more than 40 fixes is a release-note count, not a measurement of mainnet reliability.

One advertised component remains outside the mainnet change. Cronos says the version 1.8 code contains experimental libp2p networking support, but its October 14 announcement explicitly says that networking stack is not enabled on mainnet.

What remains to verify

A scheduled date and available binary do not prove activation. The independent report reviewed by Coinburn likewise treated October 22 as a target and identified a completed coordinated halt, resumed block production and a network notice as the relevant confirmation points.

The next checks are whether Cronos confirms completion, whether blocks resume under the version 1.8 plan, and whether exchanges, bridges and major applications report normal service. Performance claims also require a defined post-upgrade observation window and an attributable dataset. Until those records appear, version 1.8 should be described as scheduled for October 22—not as a completed upgrade or proof of faster production performance.