We are upgrading our Stacks infrastructure to Stacks API v9.3.1 and stacks-core 4.0.4 on 2026-09-30. The API release includes a small database migration. The stacks-core release delivers bug fixes and stability improvements for more consistent block production, and introduces Clarity 7 ahead of Epoch 4.1. Brief interruptions to RPC availability may occur during the maintenance.
RPC Changes:
Stacks API (v9.3.1) - v3 fungible token balances — fixed. Results are now sorted by numeric balance value.
Stacks Core (4.0.4) - Error messages — changed. vm_error in transaction receipts, the cause field in read-only call responses, and block rejection reasons are now capped at 4096 bytes. Tuple and list values in these messages now render in Clarity syntax (e.g. (tuple (a u1))) instead of internal debug format. Users parsing these strings should update their handling. - Smart contract deploys (from Epoch 4.1) — breaking. VersionedSmartContract payloads will be rejected as invalid. Deploy using the unversioned SmartContract payload, which defaults to Clarity 7. - replace-at? (from Epoch 4.1) — fixed. A zero-length buffer or string element is now rejected at type-check time, or fails with an includable error at runtime, rather than making the transaction rejectable.