# Base’s Retired Flashblocks Feeds Stay Connected Without Sending Data By Simon Yoon Canonical URL: https://www.tokenpost.com/news/technology/53078 Published: 2026-11-10T12:34:05.000Z Updated: 2026-11-10T12:34:05.000Z Section: Technology > Apps using the old WebSocket feeds must move to canonical block and log subscriptions through a WebSocket-capable RPC provider or their own node. Base’s retired Flashblocks WebSocket feeds still accept connections but no longer send updates, leaving apps that rely on them without data and requiring developers to migrate subscriptions. [Base activated Denim on its mainnet]() at 1 p.m. ET (18:00 UTC) Nov. 5. The upgrade changed the network’s cadence from one canonical block every two seconds to five complete canonical blocks per second, or one every 200 milliseconds. It also ended the interim pending-state updates Flashblocks provided between complete blocks. The connection behavior can make the migration easy to miss: an app may stay connected to an old Flashblocks endpoint even though the feed has stopped sending data. Developers can move to canonical block and log subscriptions through a WebSocket-capable RPC provider or a node they operate. The subscription changes include replacing newFlashblocks with newHeads and pendingLogs with logs. Apps that used newFlashblockTransactions can subscribe to newHeads and then fetch transactions from each canonical block. The pending block tag remains available, but now returns the latest canonical block. Flashblocks preconfirmation data has no direct equivalent. The faster cadence also affects code that uses block counts to measure time. Such code can run 10 times faster in wall-clock terms, while block.timestamp remains measured in whole seconds. A transaction’s inclusion in a block does not make it final. Base blocks become safe when their batch is posted to Ethereum and final when Ethereum finalizes that batch. ## Links in this article - [Base activated Denim on its mainnet](https://www.tokenpost.com/news/technology/50733)