The Denim upgrade leaves applications built on Base’s retired Flashblocks feeds without new data, so developers need to reconfigure how those apps follow the network. An endpoint can remain connected after its updates stop, obscuring the need to make a change.
When Denim took effect on Base mainnet at 1 p.m. ET (18:00 UTC) Thursday, Nov. 5, canonical blocks shifted to a 200-millisecond cadence, or five a second, from one every two seconds.
That shorter interval also affects software that uses block counts as a clock: routines may reach a target 10 times sooner in wall-clock time, while block.timestamp continues to record time in whole seconds.
The canonical subscription pairs are newHeads for apps formerly using newFlashblocks and logs for those that used pendingLogs. An app that depended on newFlashblockTransactions can listen for each newHeads event and inspect the transactions in the corresponding canonical block. A pending request now resolves to the latest canonical block; the canonical feeds do not carry Flashblocks’ preconfirmation data. Developers can route subscriptions through an RPC service that supports WebSockets or use a node they operate.
