Release Notes
Fix: Block Template Builder Using Outdated Block Max Mass
While developing Nocturne, the logic for determining block version was moved from node startup into consensus. This allowed consensus to dynamically pull the correct settings and ensure smooth transitions between versions (e.g., from Block V4 to V5).
However, one instance of this logic was overlooked: the Block Template Builder. Unlike consensus, the template builder was still determining block max mass at node startup instead of pulling it on demand. As a result, nodes have been applying Block V4 maximum mass limits, even when consensus already allows larger Block V5 blocks.
Impact
- Nodes starting on outdated block versions can still validate blocks, but they will only produce blocks limited to ~246 transactions per block (in 1-in, 2-out transactions).
- Consensus itself correctly allows up to 2× that size, so the network does not require a hard fork.
- The issue affects only block production, not validation.
Fix & Upgrade Path
- The Block Template Builder has been updated to pull block max mass settings dynamically, ensuring alignment with consensus.
- No hard fork is required.
- Node operators only need to upgrade if they want to participate in creating larger blocks.
Discovery
This issue was identified during testing of Rothschild spamming on mainnet, which revealed a mismatch when blocks consistently capped out at 246 transactions.