We are upgrading our Stacks Mainnet infrastructure to stacks-core v4.0.4 on 2026-10-07. This is a stability and bugfix release addressing block production consistency, signature verification corrections in the Wasm backend, and removal of deprecated transaction-replay configuration. Brief interruptions to RPC availability may occur on that date.
RPC Changes: - /v3/tenures/fork_info — The nakamoto_blocks field is now always null and is deprecated; it will be removed in a future release. - read-only function error cause — Error messages (including read-only call cause payloads) are now clamped to 4096 bytes at construction; Tuple and list values in error messages now render in Clarity syntax instead of internal debug format. - SmartContract deploy payload — Versioned smart-contract deploys (VersionedSmartContract payload) are rejected as statically invalid from Epoch 4.1 onwards; deploy new contracts using the unversioned SmartContract payload, which uses the epoch's default Clarity version. - Clarity 7 support — Epoch 4.1 introduces Clarity 7 as the default version; public or read-only functions may now take reserved names to implement trait methods from earlier Clarity versions that had those names free.