Coinbase’s Base blockchain retired its Flashblocks knowledge feeds within the Nov. 5 Denim improve, requiring apps utilizing them emigrate. The outdated WebSocket endpoints nonetheless settle for connections however now not ship knowledge, in line with Base’s migration instructions.
Denim activated on mainnet at 18:00 UTC on Nov. 5. Base’s upgrade overview describes full canonical blocks each 200 milliseconds, every with its personal hash, state root and receipts. These are the chain’s blocks quite than previews of a block nonetheless being constructed.
The compatibility lure is that an open connection now not establishes that an app is receiving updates. Reconnecting to a retired Flashblocks endpoint leaves the underlying integration downside unresolved.
Change the Flashblocks knowledge route and evaluation what pending-state requests now return.
Schematic routes, not measured site visitors or transaction-inclusion latency. Canonical block inclusion stays separate from Ethereum finality.
What apps want to vary
Base directs builders to interchange Flashblocks connections with subscriptions via a WebSocket-capable RPC supplier or their very own node. Its alternative map has three major subscription adjustments:
newFlashblocksturns intonewHeads, which follows canonical block headers.pendingLogsturns intologs.newFlashblockTransactionsturns intonewHeads, adopted by fetching the transactions in every canonical block.
Builders should additionally evaluation what their apps anticipate from the pending block tag. Base nonetheless accepts that tag, but it surely now resolves to the most recent canonical block. It now not exposes Flashblocks preconfirmation state, and there’s no direct equal for that former preview.
That change issues for requests studying balances, transaction counts or simulated contract outcomes towards pending state. An software retaining the outdated assumption can mistake an accepted response for a preview though it’s studying canonical state.
Transaction dealing with adjustments too. Apps can preserve polling eth_getTransactionReceipt, however a receipt turns into obtainable as soon as the transaction enters a canonical 200ms block. Preconfirmed receipts and preconfirmed transaction outcomes are now not obtainable.
Base recommends inventorying Flashblocks subscriptions, WebSocket connections and pending-tag requests, together with flashblock_index utilization and node flags. It advises testing migrated integrations on Base Sepolia or Vibenet.
Base’s Denim upgrade notice, nonetheless marked “Verifying” on Nov. 9, carried a Nov. 5 replace at 18:14 UTC reporting an investigation into periodic transaction inclusion delays and the next than anticipated fee of empty blocks. The discover contained no subsequent decision replace.
A 200ms block cadence describes how typically blocks arrive; it doesn’t promise that each submitted transaction enters the following block. Inclusion additionally stays separate from finality. In its Denim announcement, Base says a block turns into protected when its batch is posted to Ethereum and last when Ethereum finalizes that batch. Apps needing these stronger ensures nonetheless have to differentiate them from the arrival of a canonical block.
