Base Denim upgrade brings 200ms blocks to mainnet

Base activated its Denim upgrade on mainnet on Nov. 5, replacing Flashblocks with canonical blocks produced every 200 milliseconds. Before the change, the network produced one canonical block every two seconds.

• Five canonical blocks per second
• 200 milliseconds between blocks
• Activation began at 18:00 UTC on Nov. 5

Base’s Denim announcement says each update is now a full block rather than a preview of a block still being built. The change removes the separate Flashblocks stream and pending-state updates.

What changes for apps and users?

Apps can read the faster cadence through standard blockchain feeds, according to Base. Developers that relied on Flashblocks subscriptions or pending-state data need to move to canonical block feeds such as newHeads and logs.

Base says transactions included in a block are not automatically final. A block becomes safe when its batch is posted to Ethereum and final when Ethereum finalizes that batch.

The faster block count also changes software that measures time by counting blocks. Base warns that a fixed block-count duration will elapse in one-tenth the time it did before Denim; the EVM’s second-based block.timestamp remains unchanged.

What remains under review?

Base’s status update says Denim activated successfully, but the network team is investigating periodic transaction-inclusion delays and a higher-than-expected rate of empty blocks. The update does not give a cause or resolution time.

That leaves the launch confirmed, while the operational effects flagged during verification remain open. Base’s status page lists block production as operational, but reports degraded performance for the transaction pool.

Source material

• Denim announcement — base.org
• status update — base-l2.statuspage.io